EMC FC5300, FC4500, FC5700 User Manual

EMC Enterprise Storage

EMC Fibre Channel Storage Systems

Models FC4500, FC5300, and FC5700

CONFIGURATION PLANNING GUIDE

P/N 014003039-02

EMC Corporation 171 South Street, Hopkinton, MA 01748-9103

Corporate Headquarters: [phone], (800) 424-EMC2 Fax: [phone] Service: (800) SVC-4EMC

Copyright © EMC Corporation 2000, 2001. All rights reserved.

Printed May 2001

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ii

EMC Fibre Channel Storage Systems Configuration Planning Guide

Contents

Preface..............................................................................................................................xi

Chapter 1 About Fibre Channel Storage Systems and Networks

(SANs)

Introducing EMC Fibre Channel Storage Systems.......................1-2

Fibre Channel Background..............................................................1-3

Fibre Channel Storage Components ..............................................1-4

Server Component (Host-Bus Adapter Driver Package with

Software).....................................................................................1-4

Interconnect Components ........................................................1-4

Storage Component (Storage Systems, Storage Processors

(SPs), and Other Hardware).....................................................1-9

Types of Storage System Installations..........................................1-10

About Switched Shared Storage and SANs (Storage Area

Networks) ........................................................................................1-11

Storage Groups.........................................................................1-12

Storage System Hardware for Shared Storage....................1-15

About Unshared Storage ...............................................................1-16

Storage System Hardware for Unshared Storage...............1-16

Chapter 2 RAID Types and Tradeoffs

Introducing RAID.............................................................................2-2

Disk Striping...............................................................................2-2

Mirroring.....................................................................................2-2

RAID Groups and LUNs ..........................................................2-3

RAID Types........................................................................................2-4

RAID 5 Group (Individual Access Array) .............................2-4

RAID 3 Group (Parallel Access Array)...................................2-5

EMC Fibre Channel Storage Systems Configuration Planning Guide

iii

Contents

RAID 1 Mirrored Pair ...............................................................2-7

RAID 0 Group (Nonredundant Array) ..................................2-8

RAID 1/0 Group (Mirrored RAID 0 Group).........................2-8

Individual Disk Unit .................................................................2-9

Hot Spare....................................................................................2-9

RAID Benefits and Tradeoffs.........................................................2-12

Performance .............................................................................2-13

Storage Flexibility....................................................................2-14

Data Availability and Disk Space Usage..............................2-14

Guidelines for RAID Types ...........................................................2-17

Sample Applications for RAID Types..........................................2-19

Chapter 3 Planning File Systems and LUNs with Shared Switched

Storage

Dual Paths to LUNs..........................................................................3-2

Sample Shared Switched Installation ............................................3-3

Planning Applications, LUNs, and Storage Groups....................3-6

Application and LUN Planning ..............................................3-6

Application and LUN Planning Worksheet ..........................3-7

LUN and Storage Group Planning Worksheet .....................3-8

LUN Details Worksheet..........................................................3-11

Chapter 4 Planning LUNs and File Systems with Unshared Direct

Storage

Dual SPs and Paths to LUNs...........................................................4-2

Unshared Direct and Shared-or-Clustered Direct Storage .........4-2

Sample Unshared Direct Installation......................................4-2

Sample Shared-or-Clustered Direct Installation...................4-3

Planning Applications and LUNs..................................................4-4

Application and LUN Planning ..............................................4-4

Application and LUN Planning Worksheet ..........................4-5

LUN Planning Worksheet........................................................4-6

Completing the LUN Details Worksheet.............................4-12

Chapter 5 Storage System Hardware

Hardware for Shared Storage .........................................................5-3

Storage Hardware — Rackmount DPE-Based Storage

Systems .......................................................................................5-3

Disks............................................................................................5-4

Storage Processor (SP) ..............................................................5-5

iv

EMC Fibre Channel Storage Systems Configuration Planning Guide

Contents

Hardware for Unshared Storage....................................................5-6

Types of Storage System for Unshared Storage ................... 5-6

Disks............................................................................................ 5-8

Storage Processor (SP).............................................................. 5-9

Planning Your Hardware Components ...................................... 5-11

Configuration Tradeoffs - Shared Storage .......................... 5-11

Configuration Tradeoffs - Unshared Storage ..................... 5-12

Hardware Data Sheets................................................................... 5-14

DPE Data Sheet........................................................................ 5-14

iDAE Data Sheet...................................................................... 5-16

DAE Data Sheet....................................................................... 5-18

Cabinets for Rackmount Enclosures............................................ 5-20

Cable and Configuration Guidelines .......................................... 5-21

Hardware Planning Worksheets.................................................. 5-24

Hardware for Shared Storage ...............................................5-24

Hardware Component Worksheet for Shared Storage...... 5-25

Hardware Component Worksheet for Shared Storage...... 5-27

Hardware for Unshared Storage ..........................................5-27

Hardware Component Worksheet for Unshared Storage. 5-30

Hardware Component Worksheet for Unshared Storage. 5-31

Hardware Component Worksheet for Unshared Storage. 5-33

Hardware Component Worksheet for Unshared Storage. 5-35

Chapter 6 Storage-System Management

Using Navisphere Manager Software........................................... 6-3

Storage Management Worksheets.................................................. 6-5

Index ................................................................................................................................i-1

EMC Fibre Channel Storage Systems Configuration Planning Guide

v

Contents

vi

EMC Fibre Channel Storage Systems Configuration Planning Guide

Figures

1-1 Storage System Models ................................................................................ 1-2

1-2 Nodes - Initiator and Target ....................................................................... 1-3

1-3 Switch and Hub Topologies Compared .................................................... 1-6

1-4 A Switch Zone ............................................................................................... 1-7

1-5 16-Port Switch, Back View .......................................................................... 1-7

1-6 Nine-Port Hub .............................................................................................. 1-8

1-7 Disk-Array Processor Enclosure (DPE) ..................................................... 1-9

1-8 Types of Storage System Installation ....................................................... 1-10

1-9 Components of a SAN ............................................................................... 1-11

1-10 Sample SAN Configuration ...................................................................... 1-13

1-11 Data and Configuration Access Control with Shared Storage ............ 1-14

1-12 Storage System with a DPE and Three DAEs ........................................ 1-15

1-13 Storage System Hardware for Unshared Storage .................................. 1-17

2-1 Multiple LUNs in a RAID Group ............................................................... 2-3

2-2 RAID 5 Group ............................................................................................... 2-5

2-3 RAID 3 Group ............................................................................................... 2-6

2-4 RAID 1 Mirrored Pair .................................................................................. 2-7

2-5 RAID 1/0 Group (Mirrored RAID 0 Group) ............................................ 2-9

2-6 How a Hot Spare Works ............................................................................ 2-11

2-7 Disk Space Usage in the RAID Configurations ...................................... 2-16

3-1 Sample Shared Switched High Availability installation ........................ 3-3

4-1 Unshared Direct Installation ....................................................................... 4-2

4-2 Sample Clustered Installation ..................................................................... 4-3

5-1 Shared and Unshared Storage .................................................................... 5-2

5-2 DPE Storage-System Components – Rackmount Model ........................ 5-3

5-3 Rackmount System with DPE and DAEs .................................................. 5-4

5-4 Shared Storage Systems ............................................................................... 5-5

5-5 Storage System Types for Unshared Storage ........................................... 5-7

5-6 DPE Components - Deskside Model ......................................................... 5-8

5-7 Disks and Disk IDs ....................................................................................... 5-9

EMC Fibre Channel Storage-System Configuration Planning Guide

vii

Figures

5-8 Storage System with Two SPs Connected to the Same Server ............. 5-10

5-9 Storage System with Two SPs Connected to Different Servers ............ 5-10

5-10 Comparison Between Optical and Copper Cabling ............................... 5-21

5-11 Cable Identifier — DPE-Based System for Shared Storage ................... 5-24

5-12 Sample Shared Storage Installation .......................................................... 5-26

5-13 Cable Identifier — Unshared System without Hubs ............................. 5-28

5-14 Cable Identifier — Unshared Full-Fibre System with Hubs ................. 5-29

5-15 Sample Unshared Deskside System — Basic Configuration ................ 5-31

5-16 Sample Unshared Deskside System — Dual-Adapter/Dual-SP

Configuration ............................................................................................... 5-32

5-17 Sample Component Worksheet for DPE-Based System with Hubs — Two

Loops.............................................................................................................. 5-34

6-1 Sample Shared Switched Environment with Navisphere Manager ...... 6-4

6-2 Sample Unshared Environment with Navisphere Manager .................. 6-4

viii

EMC Fibre Channel Storage-System Configuration Planning Guide

Tables

2-1 Performance, Availability, and Cost of RAID Types

(Individual Unit = 1.0) ............................................................................... 2-13

3-1 Cache Recommendations for Different RAID Types ............................ 3-16

4-1 Cache Recommendations for Different RAID Types ............................ 4-15

5-1 High-Availability Options, Deskside Unshared Storage ...................... 5-13

5-2 High-Availability Options, Rackmount Unshared Storage ................. 5-13

5-3 Cable Sizes — Optical ............................................................................ 5-22

5-4 Cable Sizes — Copper ................................................................................ 5-23

EMC Fibre Channel Storage-System Configuration Planning Guide

ix

Tab les

x

EMC Fibre Channel Storage-System Configuration Planning Guide

Audience for the Manual

Preface

This planning guide provides an overview of Fibre Channel
disk-array storage-system models and offers essential background
information and worksheets to help you with the installation and
configuration planning.

Please read this guide

• if you are considering purchase of an EMC Fibre Channel
disk-array storage system and want to understand its features; or

• before you plan the installation of a storage system.

You should be familiar with the host servers that will use the storage
systems and with the operating systems of the servers. After reading
this guide, you will be able to

• determine the best storage system components for your
installation

• determine your site requirements

• configure storage systems correctly

EMC Fibre Channel Storage-System Configuration Planning Guidexi

xi

Preface

Organization of the Manual

Chapter 1 Provides background information on the Fibre

Channel protocols and explains the major installation
types.

Chapter 2 Describes the RAID Groups and the different ways

they store data.
Chapter 3 Describes installations for shared switched storage.
Chapter 4 Describes installations for unshared direct, and

shared-or-clustered direct, and shared switched

storage.
Chapter 5 Describes hardware components.
Chapter 6 Describes storage-system management utilities.

xii

EMC Fibre Channel Storage-System Configuration Planning Guide

1

About Fibre Channel

Storage Systems and

Networks (SANs)

This chapter introduces Fibre Channel disk-array storage systems
and storage area networks (SANs). Major sections are

• Introducing EMC Fibre Channel Storage Systems........................1-2

• Fibre Channel Background...............................................................1-3

• Fibre Channel Storage Components................................................1-4

• About Switched Shared Storage and SANs (Storage Area

Networks).......................................................................................... 1-11

• About Unshared Storage.................................................................1-16

About Fibre Channel Storage Systems and Networks (SANs)

1-1

About Fibre Channel Storage Systems and Networks (SANs)

1

Introducing EMC Fibre Channel Storage Systems

EMC Fibre Channel disk-array storage systems provide terabytes of
disk storage capacity, high transfer rates, flexible configurations, and
highly available data at low cost.

A storage system package includes a host-bus adapter driver package
with hardware and software to connect with a server, storage
management software, Fibre Channel interconnect hardware, and
one or more storage systems.

1-2

Figure 1-1 Storage System Models

EMC Fibre Channel Storage-System Configuration Planning

Fibre Channel Background

Fibre Channel is a high-performance serial protocol that allows
transmission of both network and I/O channel data. It is a low level
protocol, independent of data types, and supports such formats as
SCSI and IP.

The Fibre Channel standard supports several physical topologies,
including switched fabric point-to-point and arbitrated loop (FC-AL).
The topologies used by the Fibre Channel storage systems described
in this manual are switched fabric and FC-AL.

A switch fabric is a set of point-to-point connections between nodes,
the connection being made through one or more Fibre Channel
switches. Each node may have its own unique address, but the path
between nodes is governed by a switch. The nodes are connected by
optical cable.

A Fibre Channel arbitrated loop is a circuit consisting of nodes. Each
node has a unique address, called a Fibre Channel arbitrated loop
address. The nodes are connected by optical cables. An optical cable
can transmit data over great distances for connections that span
entire enterprises and can support remote disaster recovery systems.
Copper cable serves well for local connections; its length is limited to
30 meters (99 feet).

About Fibre Channel Storage Systems and Networks (SANs)

1

Each connected device in a switched fabric or arbitrated loop is a
server adapter (initiator) or a target (storage system). The switches
and hubs are not considered nodes.

Server Adapter (initiator)

Node

Adapter

Storage System (tar

Connection

Figure 1-2 Nodes - Initiator and Target

Node

get)

EMC1802

Fibre Channel Background

1-3

About Fibre Channel Storage Systems and Networks (SANs)

1

Fibre Channel Storage Components

A Fibre Channel storage system has three main components:

• Server component (host-bus adapter driver package with adapter

and software)

• Interconnect components (cables based on Fibre Channel

standards, switches, and hubs)

• Storage components (storage system with storage processors —

SPs — and power supply and cooling hardware)

Server Component (Host-Bus Adapter Driver Package with Software)

The host-bus adapter driver package includes a host-bus adapter and
support software. The adapter is a printed-circuit board that slides
into an I/O slot in the server’s cabinet. It transfers data between
server memory and one or more disk-array storage systems over
Fibre Channel — as controlled by the support software (adapter
driver).

Interconnect Components

Cables Depending on your needs, you can choose copper or optical cables.

1-4

EMC Fibre Channel Storage-System Configuration Planning

One or more servers can use a storage system. For high availability —
in event of an adapter failure — a server can have two adapters.

Server

Adapter

Adapter

EMC1803

Depending on your server type, you may have a choice of adapters.
The adapter is designed for a specific host bus; for example, a PCI bus
or SBUS. Some adapter types support copper or optical cabling; some
support copper cabling only.

The interconnect components include the cables, Fibre Channel
switch (for shared storage), and Fibre Channel hub (for unshared
storage).

Fibre Channel Switches

About Fibre Channel Storage Systems and Networks (SANs)

1

The maximum length of copper cable is 30 meters (99 feet) between
nodes or hubs. The maximum length of optical cable between server
and hub or storage system is much greater, depending on the cable
type. For example, 62.5-micron multimode cable can span up to 500
meters (1,640 feet) while 9-micron single-mode cable can span up to
10 kilometers (6.2 miles). This ability to span great distances is a
major advantage of optical cable.

Some nodes have connections that require a specific type of cable:
copper or optical. Other nodes allow for the conversion from copper
to optical using a conversion device called a GigaBit Interface
Converter (GBIC) or Media Interface Adapter (MIA). In most cases, a
GBIC or MIA lets you substitute long-distance optical connections for
shorter copper connections.

With extenders, optical cable can span up to 40 km (25 miles). This
ability to span great distances is a major advantage of optical cable.

Details on cable lengths and rules appear later in this manual.

A Fibre Channel switch, which is a requirement for shared storage (a
Storage Area Network, SAN) connects all the nodes cabled to it using
a fabric topology. A switch adds serviceability and scalability to any
installation; it allows on-line insertion and removal of any device on
the fabric and maintains integrity if any connected device stops
participating. A switch also provides host-to-storage-system access
control in a multiple-host shared-storage environment. A switch has
several advantages over a hub: it provides point-to-point connections
(as opposed to a hub’s loop that includes all nodes) and it offers
zoning to specify paths between nodes in the switch itself.

Fibre Channel Storage Components

1-5

About Fibre Channel Storage Systems and Networks (SANs)

1

You can cascade switches (connect one switch port to another switch)
for additional port connections.

Switch topology (point-to-point)

Server

Adapter

Hub uses
loop between
ports

SP SP

Server

Adapter

SP

Adapter

Storage systems

Server Server

Adapter

witch uses discrete
onnections between
orts

o illustrate the comparison, this figure shows just one adapter per server and one switch or

hub. Normally, such installations include two adapters per server and two switches or hubs.

Figure 1-3 Switch and Hub Topologies Compared

Hub topology (loop)

Server

Adapter

SP

Switch Zoning

Switch zoning defines paths between connected nodes. Each zone
encloses one or more adapters and one or more SPs. A switch can
have as many zones as it has ports. The current connection limits are
four SP ports to one adapter port (the SPs fan in to the adapter) and
15 adapters to one SP (the SPs fan out to the adapters). There are
several zone types, including the single-initiator type, which is the
recommended type.

Server

Adapter

1-6

In the following figure, Server 1 has access to one SP (SP A) in storage
systems 1 and 2; it has no access to any other SP.

EMC Fibre Channel Storage-System Configuration Planning

About Fibre Channel Storage Systems and Networks (SANs)

Server 1

1

Adapter

Zone

SP SP

Storage system 1

To illustrate switch zoning, this figure shows just one HBA per server and one
switch or hub. Normally, such installations will include two HBAs per server
and two switches or hubs.

Figure 1-4 A Switch Zone

If you do not define a zone in a switch, all adapter ports connected to
the switch can communicate with all SP ports connected to the
switch. However, access to an SP does not necessarily provide access
to the SP’s storage; access to storage is governed by the Storage
Groups you create (defined later).

Adapter

Switch

fabric

SP

Storage system 2 Storage system 3

Adapter

SP

SP

SP

Fibre Channel switches are available with 16 or 8 ports. They are
compact units that fit in 2 U (3.5 inches) for the 16-port or 1 U (1.75
inches) for the 8-port. They are available to fit into a rackmount
cabinet or as small deskside enclosures.

Ports

Figure 1-5 16-Port Switch, Back View

EMC1807

Fibre Channel Storage Components

1-7

About Fibre Channel Storage Systems and Networks (SANs)

1

If your servers and storage systems will be far apart, you can place
the switches closer to the servers or the storage systems, as
convenient.

A switch is technically a repeater, not a node, in a Fibre Channel loop.
However, it is bound by the same cabling distance rules as a node.

Fibre Channel Hubs A hub connects all the nodes cabled to it into a single logical loop. A

hub adds serviceability and scalability to any loop; it allows on-line
insertion and removal of any device on the loop and maintains loop
integrity if any connected device stops participating.

Fibre channel hubs are compact units that fit in 1 U (1.75 inches) of
storage space. They are available to fit into a rackmount cabinet or as
small deskside units.

1-8

The nine-pin port can connect to a server,
storage system, or another hub.

Figure 1-6 Nine-Port Hub

If your servers and storage systems will be far apart, you can place
the hubs closer to the servers or the storage systems, as convenient.

EMC Fibre Channel Storage-System Configuration Planning

About Fibre Channel Storage Systems and Networks (SANs)

Storage Component (Storage Systems, Storage Processors (SPs), and Other Hardware)

EMC disk-array storage systems, with their storage processors,
power supplies, and cooling hardware form the storage component
of a Fibre Channel system. The controlling unit, a Disk-array
Processor Enclosure (DPE) looks like the following figure.

Disk
modules

EMC1808

Figure 1-7 Disk-Array Processor Enclosure (DPE)

1

DPE hardware details appear in a later chapter.

Fibre Channel Storage Components

1-9

About Fibre Channel Storage Systems and Networks (SANs)

1

Types of Storage System Installations

You can use a storage systems in any of several types of installation:

• Unshared direct with one server is the simplest and least costly;

• Shared-or-clustered direct lets two clustered servers share

storage resources with high availability (FC4500 storage systems;
and

• Shared switched, with one or two switch fabrics, lets two to 15
servers share the resources of several storage systems in a Storage
Area Network (SAN) Shared switched installations are available
in a high-availability (HA) version, with two HBAs per server,
with two switches, or with one HBA per server and one switch.

Unshared Direct

(one or two servers)

Server

Adapter

Adapter

Path 1

Path 2

Figure 1-8 Types of Storage System Installation

Shared-or-Clustered Direct

(two servers)

Adapter

Server

Adapter

Adapter

Server

Adapter

Disk-array storage systems

Shared Switched

(multiple servers)

Server

Adapter

Switch fabric Switch fabric

Server

Adapter

Adapter

Adapter

Server

Adapter

Adapter

Storage systems for any shared installation require EMC Access
Logix™ software to control server access to the storage system LUNs.

The Shared-or-clustered direct installation may be either shared (that
is, use Access Logix to control LUN access) or clustered (without
Access Logix, using cluster software to control LUN access),
depending on the hardware model.

1-10

EMC Fibre Channel Storage-System Configuration Planning

About Fibre Channel Storage Systems and Networks (SANs)

About Switched Shared Storage and SANs (Storage Area Networks)

This section explains the features that let multiple servers share
disk-array storage systems on a SAN (storage area network).

A SAN is a collection of storage devices connected to servers via Fibre
Channel switches to provide a central location for disk storage.
Centralizing disk storage among multiple servers has many
advantages, including

• highly available data

• flexible association between servers and storage capacity

• centralized management for fast, effective response to users’ data

storage needs

• easier file backup and recovery
An EMC SAN is based on shared storage; that is, the SAN requires

the Access Logix option to provides flexible access control to storage
system LUNs.

1

Server Server

Adapter

Adapter

Storage systems

Figure 1-9 Components of a SAN

Adapter

Switch fabric

Fibre Channel switches can control data access to storage systems
through the use of switch zoning. With zoning, an administrator can
specify groups (called zones) of Fibre Channel devices (such as
host-bus adapters, specified by worldwide name), and SPs between
which the switch will allow communication.

About Switched Shared Storage and SANs (Storage Area Networks)

SP A

Adapter

SP B

Switch fabric

SP A SP B

Server

Adapter

Adapter

Path 1

Path 2

1-11

About Fibre Channel Storage Systems and Networks (SANs)

1

However, switch zoning cannot selectively control data access to
LUNs in a storage system, because each SP appears as a single Fibre
Channel device to the switch. So switch zoning can prevent or allow
communication with an SP, but not with specific disks or LUNs
attached to an SP. For access control with LUNs, a different solution is
required: Storage Groups.

Storage Groups

A Storage Group is one or more LUNs (logical units) within a storage
system that is reserved for one or more servers and is inaccessible to
other servers. Storage Groups are the central component of shared
storage; storage systems that are unshared do not use Storage
Groups.

When you configure shared storage, you specify servers and the
Storage Group(s) each server can read from and/or write to. The Base
Software firmware running in each storage system enforces the
server-to-Storage Group permissions.

A Storage Group can be accessed by more than one server if all the
servers run cluster software. The cluster software enforces orderly
access to the shared Storage Group LUNs.

The following figure shows a simple shared storage configuration
consisting of one storage system with two Storage Groups. One
Storage Group serves a cluster of two servers running the same
operating system, and the other Storage Group serves a UNIX
database server. Each server is configured with two independent
paths to its data, including separate host-bus adapters, switches, and
SPs, so there is no single point of failure for access to its data.

1-12

EMC Fibre Channel Storage-System Configuration Planning

About Fibre Channel Storage Systems and Networks (SANs)

Highly available cluster

File Server Mail Server Database Server

Operating
system A

Adapter

Adapter

Operating
system A

Adapter

Adapter

Operating
system B

Adapter

Adapter

1

Cluster

Storage Group

Database Server

Storage Group

Figure 1-10 Sample SAN Configuration

Access Control with Shared Storage

Access control permits or restricts a server’s access to shared storage.
There are two kinds of access control:

• Configuration access control

• Data access control

Configuration access control lets you restrict the servers through
which a user can send configuration commands to an attached
storage system.

Data access control is provided by Storage Groups. During storage
system configuration, using a management utility, the system
administrator associates a server with one or more LUNs.

Switch fabric

SP A

LUN
LUN

LUN
LUN
LUN
LUN
LUN

Switch fabric

SP B

Physical storage

systems with up to
100 disks per storage
system

Path 1

Path 2

Each server sees its Storage Group as if it were an entire storage
system, and never sees the other LUNs on the storage system.
Therefore, it cannot access or modify data on LUNs that are not part
of its Storage Group. However, you can define a Storage Group to be
accessible by more than one server, if, as shown above, the servers
run cluster software.

About Switched Shared Storage and SANs (Storage Area Networks)

1-13

About Fibre Channel Storage Systems and Networks (SANs)

1

The following figure shows both data access control (Storage Groups)
and configuration access control. Each server has exclusive read and
write access to its designated Storage Group. Of the four servers
connected to the SAN, only the Admin server can send configuration
commands to the storage system.

Highly available cluster

Admin server

Operating
system A

Adapter

Adapter

01

02

Admin Storage Group
Dedicated
Data access by adapters 01, 02

Inventory Storage Group
Dedicated
Data access by adapters 03, 04

E-mail and Web server
Storage Group

Shared
Data access by
adapters 05, 06, 07, 08

Inventory server

Operating
system A

Adapter

03

Switch fabric

Adapter

04

SP A

E-mail server

Operating
system B

Adapter

Adapter

05

06

Switch fabric

SP B

LUN
LUN
LUN
LUN
LUN
LUN
LUN
LUN

LUN
LUN

Web server

Operating
system B

Adapter

Adapter

07

08

Configuation access, by
adapters 01and 02
(Admin server only)

1-14

Figure 1-11 Data and Configuration Access Control with Shared Storage

EMC Fibre Channel Storage-System Configuration Planning

Storage System Hardware for Shared Storage

For shared storage, you need a Disk-array Processor Enclosure (DPE)
storage system.

A DPE is a 10-slot enclosure with hardware RAID features provided
by one or two storage processors (SPs). For shared storage, two SPs
are required. In addition to its own disks, a DPE can support up to
nine 10-slot Disk Array Enclosures (DAEs) for a total of 100 disks.

DAE

DAE

DAE

About Fibre Channel Storage Systems and Networks (SANs)

1

DPE

Standby power
supply (SPS)

Figure 1-12 Storage System with a DPE and Three DAEs

About Switched Shared Storage and SANs (Storage Area Networks)

EMC1741

1-15

About Fibre Channel Storage Systems and Networks (SANs)

1

About Unshared Storage

Unshared storage systems are less costly and less complex than
shared storage systems. They offer many shared storage system
features; for example, you can use multiple unshared storage systems
with multiple servers. However, with multiple servers, unshared
storage offers less flexibility and security than shared storage, since
any user with write access to a privileged server’s files can enable
access to any storage system.

Storage System Hardware for Unshared Storage

For unshared storage, there are four types of storage system, each
using the FC-AL protocol. Each type is available in a rackmount or
deskside (office) version.

• Disk-array Processor Enclosure (DPE) storage systems. A DPE is
a 10-slot enclosure with hardware RAID features provided by one
or two storage processors (SPs). In addition to its own disks, a
DPE can support up to 110 additional disks in 10-slot Disk Array
Enclosures (DAEs) for a total of 120 disks. This is the same type of
storage system used for shared storage, but it has a different SP
and different Core Software.

1-16

• Intelligent Disk Array Enclosure (iDAE). An iDAE, like a DPE,
has SPs and thus all the features of a DPE, but is thinner and has a
limit of 30 disks.

• Disk Array Enclosure (DAE). A DAE does not have SPs. A DAE
can connect to a DPE or an iDAE, or you can use it without SPs. A
DAE used without an SP does not inherently include RAID, but
can operate as a RAID device using software running on the
server system. Such a DAE is also known as Just a Box of Disks, or
JBOD.

EMC Fibre Channel Storage-System Configuration Planning

About Fibre Channel Storage Systems and Networks (SANs)

Disk-array processor enclosure (DPE)

1

Deskside DPE with DAE

Intelligent disk-array enclosure (iDAE)

30-slot deskside Rackmount10-slot deskside

Rackmount DPE, one enclosure,
supports up to 9 DAEs

Figure 1-13 Storage System Hardware for Unshared Storage

What Next? For information about RAID types and RAID tradeoffs, continue to

the next chapter. To plan LUNs and file systems for shared storage,
skip to Chapter 3; or for unshared storage, Chapter 4. For details on
the storage-system hardware — shared and unshared — skip to
Chapter 5. For storage-system management utilities, skip to
Chapter 6.

About Unshared Storage

1-17

About Fibre Channel Storage Systems and Networks (SANs)

1

1-18

EMC Fibre Channel Storage-System Configuration Planning

2

RAID Types and

Tradeoffs

This chapter explains RAID types you can choose for your storage
system LUNs. If you already know about RAID types and know
which ones you want, you can skip this background information and
skip to Chapter 5. Topics are

• Introducing RAID ..............................................................................2-2

• RAID Types.........................................................................................2-4

• RAID Benefits and Tradeoffs..........................................................2-12

• Guidelines for RAID Types.............................................................2-17

• Sample Applications for RAID Types ...........................................2-19

This chapter applies primarily to storage systems with storage processors
(SPs). For a storage system without SPs (a DAE-only or JBOD system), RAID
types are limited by the RAID software you run on the server. The RAID
terms and definitions used here conform to generally accepted standards.

RAID Types and Tradeoffs

2-1

RAID Types and Tradeoffs

2

Introducing RAID

The storage system uses RAID (redundant array of independent
disks) technology. RAID technology groups separate disks into one
logical unit (LUN) to improve reliability and/or performance.

The storage system supports five RAID levels and two other disk
configurations, the individual unit and the hot spare (global spare).
You group the disks into one RAID Group by binding them using a
storage-system management utility.

Four of the RAID types use disk striping and two use mirroring.

Disk Striping

Mirroring

Using disk stripes, the storage-system hardware can read from and
write to multiple disks simultaneously and independently. By
allowing several read/write heads to work on the same task at once,
disk striping can enhance performance. The amount of information
read from or written to each disk makes up the stripe element size.
The stripe size is the stripe element size multiplied by the number of
disks in a group. For example, assume a stripe element size of 128
sectors (the default) and a five-disk group. The group has five disks,
so you would multiply five by the stripe element size of 128 to yield a
stripe size of 640 sectors.

The storage system uses disk striping with most RAID types.

Mirroring maintains a second (and optionally through software, a
third) copy of a logical disk image that provides continuous access if
the original image becomes inaccessible. The system and user
applications continue running on the good image without
interruption. There are two kinds of mirroring: hardware mirroring,
in which the SP synchronizes the disk images; and software
mirroring, in which the operating system synchronizes the images.
Software mirroring consumes server resources, since the operating
system must mirror the images, and has no offsetting advantages; we
mention it here only for historical completeness.

With a storage system, you can create a hardware mirror by binding
disks as a RAID 1 mirrored pair or a RAID 1/0 Group (a mirrored
RAID 0 Group); the hardware will then mirror the disks
automatically.

2-2

EMC Fibre Channel Storage-System Configuration Planning

RAID Types and Tradeoffs

2

RAID Groups and LUNs

Some RAID types let you create multiple LUNs on one RAID Group.
You can then allot each LUN to a different user, server, or application.
For example, a five-disk RAID 5 Group that uses 36-Gbyte disks
offers 144 Gbytes of space. You could bind three LUNs, say with 24,
60, and 60 Gbytes of storage capacity, for temporary, mail, and
customer files.

One disadvantage of multiple LUNs on a RAID Group is that I/O to
each LUN may affect I/O to the others in the group; that is, if traffic
to one LUN is very heavy, I/O performance with other LUNs may
degrade. The main advantage of multiple LUNs per RAID Group is
the ability to divide the enormous amount of disk space provided by
RAID Groups on newer, high-capacity disks.

RAID Group

LUN 0
temp

LUN 1
mail

LUN 2
customers

Disk Disk Disk Disk Disk

LUN 0
temp

LUN 1
mail

LUN 2
customers

LUN 0
temp

LUN 1
mail

LUN 2
customers

LUN 0
temp

LUN 1
mail

LUN 2
customers

LUN 0
temp

LUN 1
mail

LUN 2
customers

EMC1814

Figure 2-1 Multiple LUNs in a RAID Group

Introducing RAID

2-3

RAID Types and Tradeoffs

2

RAID Types

You can choose from the following RAID types: RAID 5, RAID 3,
RAID 1, RAID 0, RAID 1/0, individual disk unit, and hot spare.

RAID 5 Group (Individual Access Array)

A RAID 5 Group usually consists of five disks (but can have three to
sixteen). A RAID 5 Group uses disk striping. With a RAID 5 Group on
a full-fibre storage system, you can create up to 32 RAID 5 LUNs to
apportion disk space to different users, servers, and applications.

The storage system writes parity information that lets the group
continue operating if a disk fails. When you replace the failed disk,
the SP rebuilds the group using the information stored on the
working disks. Performance is degraded while the SP rebuilds the
group. However, the storage system continues to function and gives
users access to all data, including data stored on the failed disk.

The following figure shows user and parity data with the default
stripe element size of 128 sectors (65,536 bytes) in a five-disk RAID 5
Group. The stripe size comprises all stripe elements. Notice that the
disk block addresses in the stripe proceed sequentially from the first
disk to the second, third, and fourth, then back to the first, and so on.

2-4

EMC Fibre Channel Storage-System Configuration Planning

Stripe
si

ze

Stripe
element
size

Stripe

Blocks

0-127

512-639 1024-1151 1536-1663

First disk

Parity

Second disk

128-255 640-767 1152-1279

Parity

2048-2175

Third disk

256-383 768-895 1664-1791 2176-2303

Parity

Fourth disk

384-511 1280-1407 1792-1919 2304-2431

Parity

RAID Types and Tradeoffs

…

…

…

User data

…

Parity data

2

Parity

Figure 2-2 RAID 5 Group

896-1023 1408-1535 1920-2047 2432-2559

RAID 5 Groups offer excellent read performance and good write
performance. Write performance benefits greatly from
storage-system caching.

RAID 3 Group (Parallel Access Array)

A RAID 3 Group consists of five or more disks. The hardware always
reads from or writes to all the disks. A RAID 3 Group uses disk
striping. To maintain the RAID 3 performance, you can create only
one LUN per RAID 3 Group.

The storage system writes parity information that lets the group
continue operating if a disk fails. When you replace the failed disk,
the SP rebuilds the group using the information stored on the
working disks. Performance is degraded while the SP rebuilds the
group. However, the storage system continues to function and gives
users access to all data, including data stored on the failed disk.

Fifth disk

…

EMC1815

RAID Types

2-5

RAID Types and Tradeoffs

2

The following figure shows user and parity data with a data block
size of 2 Kbytes in a RAID 3 Group. Notice that the byte addresses
proceed from the first disk to the second, third, and fourth, then the
first, and so on.

Data block

First disk

Second disk

Third disk

5120-56311024-1535 3072-3583 7168-7679 9116-9627

Fourth disk

Fifth disk

…

…

…

User data

…

…

Parity data

EMC1816

Stripe
si

ze

Stripe
element
size

Bytes

2048-2559 4096-4607 6144-6655 8192-8603

0-511

512-1023 2560-3071 4608-5119 6656-71678604-9115

3584-40951536-2047 5632-6143 7680-8191 9628-10139

Parity Parity Parity Parity Parity

2-6

Figure 2-3 RAID 3 Group

RAID 3 differs from RAID 5 in several important ways. First, in a
RAID 3 Group the hardware processes disk requests serially; whereas
in a RAID 5 Group the hardware can interleave disk requests. Second,
with a RAID 3 Group, the parity information is stored on one disk;
with a RAID 5 Group, it is stored on all disks. Finally, with a RAID 3
Group, the I/O occurs in small units (one sector) to each disk. A
RAID 3 Group works well for single-task applications that use I/Os
of blocks larger than 64 Kbytes.

Each RAID 3 Group requires some dedicated SP memory (6 Mbytes
recommended per group). This memory is allocated when you create
the group and becomes unavailable for storage-system caching. For
top performance, we suggest that you do not use RAID 3 Groups
with RAID 5, RAID 1/0, or RAID 0 Groups, since SP processing
power and memory are best devoted to the RAID 3 Groups. RAID 1
mirrored pairs and individual units require less SP processing power,
and therefore work well with RAID 3 Groups.

EMC Fibre Channel Storage-System Configuration Planning

For each write to a RAID 3 Group, the storage system

1. Calculates the parity data.

2. Writes the new user and parity data.

RAID Types and Tradeoffs

2

RAID 1 Mirrored Pair

A RAID 1 Group consists of two disks that are mirrored
automatically by the storage-system hardware.

RAID 1 hardware mirroring within the storage system is not the same
as software mirroring or hardware mirroring for other kinds of disks.
Functionally, the difference is that you cannot manually stop
mirroring on a RAID 1 mirrored pair, and then access one of the
images independently. If you want to use one of the disks in such a
mirror separately, you must unbind the mirror (losing all data on it),
rebind the disk in as the type you want, and software format the
newly bound LUN.

With a storage system, RAID 1 hardware mirroring has the following
advantages:

• automatic operation (you do not have to issue commands to
initiate it)

• physical duplication of images

• a rebuild period that you can select during which the SP recreates

the second image after a failure

With a RAID 1 mirrored pair, the storage system writes the same data
to both disks, as follows.

First disk

0

0

1

1

2

Second disk

2

3

3

4

…

4

…

User data

EMC1817

Figure 2-4 RAID 1 Mirrored Pair

RAID Types

2-7

RAID Types and Tradeoffs

2

RAID 0 Group (Nonredundant Array)

A RAID 0 Group consists of three to a maximum of sixteen disks. A
RAID 0 Group uses disk striping, in which the hardware writes to or
reads from multiple disks simultaneously. In a full-fibre storage
system, you can create up to 32 LUNs per RAID Group.

Unlike the other RAID levels, with RAID 0 the hardware does not
maintain parity information on any disk; this type of group has no
inherent data redundancy. RAID 0 offers enhanced performance
through simultaneous I/O to different disks.

If the operating system supports software mirroring, you can use
software mirroring with the RAID 0 Group to provide high
availability. A desirable alternative to RAID 0 is RAID 1/0.

RAID 1/0 Group (Mirrored RAID 0 Group)

A RAID 1/0 Group consists of four, six, eight, ten, twelve, fourteen,
or sixteen disks. These disks make up two mirror images, with each
image including two to eight disks. The hardware automatically
mirrors the disks. A RAID 1/0 Group uses disk striping. It combines
the speed advantage of RAID 0 with the redundancy advantage of
mirroring. With a RAID 1/0 Group on a full-fibre storage system, you
can create up to 32 RAID 5 LUNs to apportion disk space to different
users, servers, and applications.

2-8

The following figure shows the distribution of user data with the
default stripe element size of 128 sectors (65,536 bytes) in a six-disk
RAID 1/0 Group. Notice that the disk block addresses in the stripe
proceed sequentially from the first mirrored disks (first and fourth
disks) to the second mirrored disks (second and fifth disks), to the
third mirrored disks (third and sixth disks), and then from the first
mirrored disks, and so on.

EMC Fibre Channel Storage-System Configuration Planning

Stripe

ze

si

Stripe
element
size

Stripe

Blocks

0-127 384-511

First disk of primary image

Second disk of primary image

512-639128-255 1664-17911280-1407896-1023

Third disk of primary image

256-383

640-767

1024-1151

1408-1535

1536-16631152-1279768-895

1792-1919

RAID Types and Tradeoffs

2

…

…

…

Figure 2-5 RAID 1/0 Group (Mirrored RAID 0 Group)

Individual Disk Unit

First disk of secondary image

384-511

768-895

1152-1279

1536-16630-127

…

User data

Second disk of secondary image

128-255

512-639

896-1023

1280-1407

1664-1791

…

Third disk of secondary image

256-383

640-767

1024-1151

1408-1535

1792-1919

…

EMC1818

A RAID 1/0 Group can survive the failure of multiple disks,
providing that one disk in each image pair survives.

An individual disk unit is a disk bound to be independent of any
other disk in the cabinet. An individual unit has no inherent high
availability, but you can make it highly available by using software
mirroring with another individual unit. You can create one LUN per
individual disk unit. If you want to apportion the disk space, you can
do so using partitions, file systems, or user directories.

Hot Spare

A hot spare is a dedicated replacement disk on which users cannot
store information. A hot spare is global: if any disk in a RAID 5
Group, RAID 3 Group, RAID 1 mirrored pair, or RAID 1/0 Group
fails, the SP automatically rebuilds the failed disk’s structure on the
hot spare. When the SP finishes rebuilding, the disk group functions
as usual, using the hot spare instead of the failed disk. When you

RAID Types

2-9

RAID Types and Tradeoffs

2

replace the failed disk, the SP copies the data from the former hot
spare onto the replacement disk.

When the copy is done, the disk group consists of disks in the original
slots, and the SP automatically frees the hot spare to serve as a hot
spare again. A hot spare is most useful when you need the highest
data availability. It eliminates the time and effort needed for someone
to notice that a disk has failed, find a suitable replacement disk, and
insert the disk.

When you plan to use a hot spare, make sure the disk has the capacity to
serve in any RAID Group in the storage-system chassis. A RAID Group
cannot use a hot spare that is smaller than a failed disk in the group.

You can have one or more hot spares per storage-system chassis. You
can make any disk in the chassis a hot spare, except for a disk that
serves for Core Software storage or the write cache vault. That is, a
hot spare can be any of the following disks:

DPE or iDAE system without write caching: disks 3-119
DPE system with write caching: disks 9-119
iDAE system with write caching: disks 5-29
30-slot SCSI-disk system: disks A1-E1, A2-E2,

B3-E3, A4-E4

2-10

An example of hot spare usage for a deskside DPE storage system
follows.

EMC Fibre Channel Storage-System Configuration Planning

RAID Types and Tradeoffs

2

10
0
1
2
3
4
5
6
7
8
9

11

12

13

14

15

16

17

18

19

1. RAID 5 group consists of disk modules 0-4; RAID 1 mirrored pair is
modules 5 and 6; hot spare is module 9.

2. Disk module 3 fails.

3. RAID 5 group becomes modules 0, 1, 2, 9, and 4; now no hot spare is
available.

4. System operator replaces failed module 3 with a functional module.

5. RAID 5 group once again is 0-4 and hot spare is 9.

Figure 2-6 How a Hot Spare Works

Hot spare

RAID Types

2-11

RAID Types and Tradeoffs

2

RAID Benefits and Tradeoffs

This section reviews RAID types and explains their benefits and
tradeoffs. You can create seven types of LUN:

• RAID 5 Group (individual access array)

• RAID 3 Group (parallel access array)

• RAID 1 mirrored pair

• RAID 1/0 Group (mirrored RAID 0 Group); a RAID 0 Group

mirrored by the storage-system hardware

• RAID 0 Group (nonredundant individual access array); no
inherent high-availability features, but can be software mirrored
if the operating system supports mirroring

• Individual unit; no inherent high-availability features but can be
software mirrored, if the operating system supports mirroring

• Hot spare; serves only as an automatic replacement for any disk
in a RAID type other than 0; does not store data during normal
system operations

2-12

Plan the disk unit configurations carefully. After a disk has been bound into a
LUN, you cannot change the RAID type of that LUN without unbinding it,
and this means losing all data on it.

The following table compares the read and write performance,
tolerance for disk failure, and relative cost per megabyte (Mbyte) of
the RAID types. Figures shown are theoretical maximums.

EMC Fibre Channel Storage-System Configuration Planning

RAID Types and Tradeoffs

Table 2-1 Performance, Availability, and Cost of RAID Types (Individual Unit = 1.0)

2

Performance

Relative read

Disk configuration

RAID 5 Group with
fivedisk s

RAID 3 Group with
fivedisks

RAID 1 mirrored pair Up to 2 Up to 1 2

RAID 1/0 Group with
10 disks

Individual unit 1 1 1

Notes: These performance numbers are not based on storage-system caching. With caching,
the performance numbers for RAID 5 writes improve significantly.

Performance multipliers vary with load on server and storage system.

performance
without cache

Up to 5 with five disks
(for small I/O requests, 2
to 8 Kbytes)

Up to 4 (for large I/O
requests)

Up to 10 Up to 5

Relative write
performance
without cache

Up to 1.25 with five disks
(for small I/O requests, 2 to
8 Kbytes)

Up to 4 (for large I/O
requests)

Relative
cost per
Mbyte

1.25

1.25

RAID 5, with individual access, provides high read throughput for
small requests (blocks of 2 to 8 Kbytes) by allowing simultaneous
reads from each disk in the group. RAID 5 write throughput is
limited by the need to perform four I/Os per request (I/Os to read
and write data and parity information). However, write caching
improves RAID 5 write performance.

RAID 3, with parallel access, provides high throughput for
sequential, large block-size requests (blocks of more than 64 Kbytes).
With RAID 3, the system accesses all five disks in each request but
need not read data and parity before writing – advantageous for large
requests but not for small ones. RAID 3 employs SP memory without
caching, which means you do not need the second SP and BBU that
caching requires.

Generally, the performance of a RAID 3 Group increases as the size of
the I/O request increases. Read performance increases rapidly with
read requests up to 1Mbyte. Write performance increases greatly for
sequential write requests that are greater than 256 Kbytes. For
applications issuing very large I/O requests, a RAID 3 LUN provides
significantly better write performance than a RAID 5 LUN.

RAID Benefits and Tradeoffs

2-13

RAID Types and Tradeoffs

2

We do not recommend using RAID 3 in the same storage-system
chassis with RAID 5 or RAID 1/0.

A RAID 1 mirrored pair has its disks locked in synchronization, but
the SP can read data from the disk whose read/write heads are closer
to it. Therefore, RAID 1 read performance can be twice that of an
individual disk while write performance remains the same as that of
an individual disk.

A RAID 0 Group (nonredundant individual access array) or RAID
1/0 Group (mirrored RAID 0 Group) can have as many I/O
operations occurring simultaneously as there are disks in the group.
Since RAID 1/0 locks pairs of RAID 0 disks the same way as RAID 1
does, the performance of RAID 1/0 equals the number of disk pairs
times the RAID 1 performance number. If you want high throughput
for a specific LUN, use a RAID 1/0 or RAID 0 Group. A RAID 1/0
Group requires at least six disks; a RAID 0 Group, at least three disks.

An individual unit needs only one I/O operation per read or write
operation.

RAID types 5, 1, 1/0, and 0 allow multiple LUNs per RAID Group. If
you create multiple LUNs on a RAID Group, the LUNs share the
RAID Group disks, and the I/O demands of each LUN affect the I/O
service time to the other LUNs. For best performance, you may want
to use one LUN per RAID Group.

Storage Flexibility

Certain RAID Group types — RAID 5, RAID 1, RAID 1/0, and RAID
0 — let you create up to 32 LUNs in each group. This adds flexibility,
particularly with large disks, since it lets you apportion LUNs of
various sizes to different servers, applications, and users. Conversely,
with RAID 3, there can be only one LUN per RAID Group, and the
group must include five or nine disks — a sizable block of storage to
devote to one server, application, or user. However, the nature of
RAID 3 makes it ideal for that single-threaded type of application.

Data Availability and Disk Space Usage

If data availability is critical and you cannot afford to wait hours to
replace a disk, rebind it, make it accessible to the operating system,
and load its information from backup, then use a redundant RAID
Group: RAID 5, RAID 3, RAID 1 mirrored pair, or RAID 1/0. Or bind
a RAID 0 Group or individual disk unit that you will later mirror
with software mirroring. If data availability is not critical, or disk

2-14

EMC Fibre Channel Storage-System Configuration Planning

RAID Types and Tradeoffs

space usage is critical, bind an individual unit or RAID 0 Group
without software mirroring.

A RAID 1 mirrored pair or RAID 1/0 Group provides very high data
availability. They are more expensive than RAID 5 or RAID 3 Groups,
since only 50 percent of the total disk capacity is available for user
data, as shown on page 2-13.

A RAID 5 or RAID 3 Group provides high data availability, but
requires more disks than a mirrored pair. In a RAID 5 or RAID 3
Group of five disks, 80 percent of the disk space is available for user
data. So RAID 5 and RAID 3 Groups use disk space much more
efficiently than a mirrored pair. A RAID 5 or RAID 3 Group is usually
more suitable than a RAID 1 mirrored pair for applications where
high data availability, good performance, and efficient disk space
usage are all of relatively equal importance.

2

RAID Benefits and Tradeoffs

2-15

RAID Types and Tradeoffs

2

RAID 5 Group RAID 3 Group

1st disk

user and parity data

2nd disk

user and parity data

3rd disk

user and parity data

4th disk

user and parity data

5th disk

user and parity data

Disk Mirror (RAID 1 mirrored pair)

1st disk

user data

2nd disk

user data

1st disk

user data

2nd disk

user data

3rd disk

user data

4th disk

user data

5th disk

parity data

50% user data
50% redundant dat

80% user data
20% parity dat

50% user data
50% redundant data

a

100% user dat

a

RAID 0 Group
(nonredundant array)

1st disk

user data

a

2nd disk

user data

3rd disk

user data

RAID 1/0 Group

1st disk

user data

2nd disk

user data

3rd disk

user data

4th disk

user data

5th disk

user data

2-16

Individual Disk Unit

User data

Figure 2-7 Disk Space Usage in the RAID Configurations

100% user dat

a

Hot Spare

Reserved

A RAID 0 Group (nonredundant individual access array) provides all
its disk space for user files, but does not provide any high availability
features.

A RAID 1/0 Group provides the best combination of performance
and availability, at the highest cost per Mbyte of disk space.

An individual unit, like a RAID 0 Group, provides no
high-availability features. All its disk space is available for user data,
as shown in the figure above.

EMC Fibre Channel Storage-System Configuration Planning

No user dat

6th disk

user data

a

EMC1820

Guidelines for RAID Types

To decide when to use a RAID 5 Group, RAID 3 Group, mirror (that
is, a RAID 1 mirrored pair or RAID 1/0 Group), a RAID 0 Group,
individual disk unit, or hot spare, you need to weigh these factors:

• Importance of data availability

• Importance of performance

• Amount of data stored

• Cost of disk space

The following guidelines will help you decide on RAID types.
Use a RAID 5 Group (individual access array) for applications

where

• Data availability is very important

• Large volumes of data will be stored

• Multitask applications use I/O transfers of different sizes

• Good read and moderate write performance are important (write

caching can improve (RAID 5 write performance)

RAID Types and Tradeoffs

2

• You want the flexibility of multiple LUNs per RAID Group

Use a RAID 3 Group (parallel access array) for applications where

• Data availability is very important

• Large volumes of data will be stored

• A single-task application uses large I/O transfers (more than 64

Kbytes). The operating system must allow transfers aligned to
start at disk addresses that are multiples of 2 Kbytes from the start
of the LUN.

Use a RAID 1 mirrored pair for applications where

• Data availability is very important

• Speed of write access is important and write activity is heavy

Use a RAID 1/0 Group (mirrored nonredundant array) for
applications where

• Data availability is critically important

• Overall performance is very important

Guidelines for RAID Types

2-17

RAID Types and Tradeoffs

2

Use a RAID 0 Group (nonredundant individual access array) for
applications where

• High availability is not important

• Overall performance is very important

Use an individual unit for applications where

• High availability is not important

• Speed of write access is somewhat important

Use a hot spare where

• In any RAID 5, RAID 3, RAID 1/0 or RAID 1 Group, high
availability is so important that you want to regain data
redundancy quickly without human intervention if any disk in
the Group fails

• Minimizing the degraded performance caused by disk failure in a
RAID 5 or RAID 3 Group is important

2-18

EMC Fibre Channel Storage-System Configuration Planning

Sample Applications for RAID Types

This section describes some types of applications in which you would
want to use a RAID 5 Group, RAID 3 Group, RAID 1 mirrored pair,
RAID 0 Group (nonredundant array), RAID 1/0 Group, or individual
unit.

RAID 5 Group (individual access array) — Useful as a database
repository or a database server that uses a normal or low percentage
of write operations (writes are 33 percent or less of all I/O
operations). Use a RAID 5 Group where multitask applications
perform I/O transfers of different sizes. Write caching can
significantly enhance the write performance of a RAID 5 Group.

For example, a RAID 5 Group is suitable for multitasking
applications that require a large history database with a high read
rate, such as a database of legal cases, medical records, or census
information. A RAID 5 Group also works well with transaction
processing applications, such as an airline reservations system, where
users typically read the information about several available flights
before making a reservation, which requires a write operation. You
could also use a RAID 5 Group in a retail environment, such as a
supermarket, to hold the price information accessed by the
point-of-sale terminals. Even though the price information may be
updated daily, requiring many write operations, it is read many more
times during the day.

RAID Types and Tradeoffs

2

RAID 3 Group — A RAID 3 Group (parallel access array) works well
with a single-task application that uses large I/O transfers (more than
64 Kbytes), aligned to start at a disk address that is a multiple of 2
Kbytes from the beginning of the logical disk. RAID 3 Groups can use
SP memory to great advantage without the second SP and battery
backup unit required for storage-system caching.

You might use a RAID 3 Group for a single-task application that does
large I/O transfers, like a weather tracking system, geologic charting
application, medical imaging system, or video storage application.

RAID 1 mirrored pair — A RAID 1 mirrored pair is useful for
logging or record-keeping applications because it requires fewer
disks than a RAID 0 Group (nonredundant array) and provides high
availability and fast write access. Or you could use it to store daily
updates to a database that resides on a RAID 5 Group, and then,
during off-peak hours, copy the updates to the database on the
RAID 5 Group.

Sample Applications for RAID Types

2-19

RAID Types and Tradeoffs

2

RAID 0 Group (nonredundant individual access array) — Use a
RAID 0 Group where the best overall performance is important. In
terms of high availability, a RAID 0 Group is less available than an
individual unit. A RAID 0 Group (like a RAID 5 Group) requires a
minimum of three disks. A RAID 0 Group serves well for an
application that uses short-term data to which users need quick
access.

RAID 1/0 Group (mirrored RAID 0 Group) — A RAID 1/0 Group
provides the best balance of performance and availability. You can
use it very effectively for any of the RAID 5 applications. A RAID 1/0
Group requires a minimum of four disks.

Individual unit — An individual unit is useful for print spooling,
user file exchange areas, or other such applications, where high
availability is not important or where the information stored is easily
restorable from backup.

The performance of an individual unit is slightly less than a standard
disk not in an storage system. The slight degradation results from SP
overhead.

Hot spare — A hot spare provides no data storage but enhances the
availability of each RAID 5, RAID 3, RAID 1, and RAID 1/0 Group in
a storage system. Use a hot spare where you must regain high
availability quickly without human intervention if any disk in such a
RAID Group fails. A hot spare also minimizes the period of degraded
performance after a RAID 5 or RAID 3 disk fails.

2-20

What Next? This chapter explained RAID Group types and tradeoffs. To plan

LUNs and file systems for shared storage, continue to Chapter 3; or
for unshared storage, skip to Chapter 4. For details on storage­system hardware — shared and unshared — skip to Chapter 5.

For storage-system management utilities, skip to Chapter 6.

EMC Fibre Channel Storage-System Configuration Planning

3

Planning File Systems

and LUNs with Shared

Switched Storage

This chapter shows a sample RAID, LUN, and Storage Group
configuration with shared storage, and then provides worksheets for
planning your own shared storage installation. Topics are

• Dual Paths to LUNs...........................................................................3-2

• Sample Shared Switched Installation..............................................3-3

• Planning Applications, LUNs, and Storage Groups.....................3-6

Planning File Systems and LUNs with Shared Switched Storage

3-1

Planning File Systems and LUNs with Shared Switched Storage

3

Dual Paths to LUNs

A shared storage system includes two or more servers, one or two
Fibre Channel switches, and one or more storage systems, each with
two SPs and Access Logix software.

With shared storage, there are two paths to each LUN in the storage
system. The storage-system software, using optional software called
Application Transparent Failover (ATF), can automatically switch to
the other path if a device (such as a host-bus adapter or cable) fails.

With unshared storage, if the server has two adapters and the storage
system has two SPs, ATF software is available as an option. With two
adapters and two SPs, ATF can perform the same function as with
shared systems: automatically switch to the other path if a device
(such as host bus adapter or cable) fails.

3-2

EMC Fibre Channel Storage-System Configuration Planning

Planning File Systems and LUNs with Shared Switched Storage

Sample Shared Switched Installation

The following figure shows a sample shared switched
(high-availability) storage system connected to three servers: two
servers in a cluster and one server running a database management
program.

Highly available cluster

3

File Server (FS) Mail Server(MS)

Operating
system A

Adapter

Adapter

Private storage

Cluster
Storage Group

Database Server

Storage Group

Operating
system A

Adapter

Switch fabric

SP A

FS R5
Files A

MS R5
ISP A mail

MS R5
Users

DS R5
Users

DS R1

LogD1

Spare

Adapter

Spare

SP B

FS R5
Files B

MS R5
ISP B mail

MS R5
Specs

DS R5
Dbase2

DS R5 (6
disks) Dbase1

Database Server(DS)

Operating
system B

Adapter

Adapter

Switch fabric

Disk IDs

4_0-4_9

3_0-3_9

2_0-2_9

1_0-1_9

0_0-0_9

Path 1

Path 2

Figure 3-1 Sample Shared Switched High Availability installation

Sample Shared Switched Installation

3-3

Planning File Systems and LUNs with Shared Switched Storage

3

The storage-system disk IDs and server Storage Group LUNs are as
follows.

Clustered System LUNs

File Server LUNs (FS) - SP B Mail Server LUNs (MS) - SP A

Disk IDs

RAID type, storage type

4_0-4_4 RAID 5, Files A
4_5-4_9 RAID 5, Files B

6_0, 6_1 – Hot spare (automatically replaces a failed disk in any server’s LUN)

RAID type, storage type

Disk IDs
2_0-2_4 RAID 5, ISP A mail

2_5-2_9 RAID 5, ISP B mail
3_0-3_4 RAID 5, Users
3_5-3_9 RAID 5, Specs

Database Server LUNs (DS) - SP A

Disk IDs
0_0, 0_ 1 RAID 1, Log file for

database Dbase1
0_4-0_9 RAID 5 (6 disks), Dbase1
1_0-1_4 RAID 5, Users
1_5-1_9 RAID 5, Dbase2

With 36-Megabyte disks, the LUN storage capacities and drive names
are as follows.

File Server — 288 Gbytes on two LUNs

FS R5

FilesA

Unit U on five disks bound as a RAID 5 Group for

144 Gbytes of storage; for file storage.

FS R5

FilesB

Unit V on five disks bound as a RAID 5 Group for

144 Gbytes of storage; for file storage.

RAID type, storage type

3-4

EMC Fibre Channel Storage-System Configuration Planning

Planning File Systems and LUNs with Shared Switched Storage

Mail Server — 576 Gbytes on four LUNs

MS R5

ISP mail

Unit O on five disks bound as a RAID 5 Group for

144 Gbytes of storage; for the mail delivered via ISP A.

MS R5

ISP mail

Unit P on five disks bound as a RAID 5 Group for

144 Gbytes of storage; for the mail delivered via ISP B.

MSR5

Users

Unit Q on five disks bound as a RAID 5 Group for

144 Gbytes of storage; for user directories and files.

MS R5

Specs

Unit R on five disks bound as a RAID 5 Group for

144 Gbytes of storage; for specifications.

Database Server — 416 Gbytes on four LUNs

DS R5

Users

Unit users on five disks bound as a RAID 5 Group for

144 Gbytes of storage; for user directories.

3

DS R5

Dbase2

DS R1

Logs

DS R5

Dbase1

Unit dbase2 on five disks bound as a RAID 5 Group

for 144 Gbytes of storage; for the second database system.

Unit logfiles on two disks bound as a RAID 1 mirrored

pair for 36 Gbytes of storage; for the database log files.

Unit dbase on six disks bound as a RAID 5 Group for

180 Gbytes of storage; for the primary database system.

Sample Shared Switched Installation

3-5

Planning File Systems and LUNs with Shared Switched Storage

3

Planning Applications, LUNs, and Storage Groups

This section helps you plan your shared storage use — the
applications to run, the LUNs that will hold them, and the Storage
Groups that will belong to each server. The worksheets to help you
do this include

• Application and LUN planning worksheet - lets you outline your
storage needs.

• LUN and Storage Group planning worksheet - lets you decide on
the disks to compose the LUNs and the LUNs to compose the
Storage Groups for each server.

• LUN details worksheet - lets you plan each LUN in detail.

Make as many copies of each blank worksheet as you need. You will
need this information later when you configure the shared storage
system.

Sample worksheets appear later in this chapter.

Application and LUN Planning

3-6

EMC Fibre Channel Storage-System Configuration Planning

Use the following worksheet to list the applications you will run and
the RAID type and size of LUN to hold them. For each application
that will run in the SAN, write the application name, file system (if
any), RAID type, LUN ID (ascending integers, starting with 0), disk
space required, and finally the name of the servers and operating
systems that will use the LUN.

Application and LUN Planning Worksheet

Planning File Systems and LUNs with Shared Switched Storage

3

Application

Application

a

il 1

M

Mail 2

Database index

File system,
partition, or drive

RAID type of
LUN

LUN
ID (hex)

A sample worksheet begins as follows:

File system,
partition, or drive

RAID type of
LUN

LUN
ID (hex)

RAID 5 0

RAID 5 1

RAI

D 1 2

Disk space
required
(Gbytes)

Disk space
required
(Gbytes)

72 G

b

72 G

b

18 G

b

Server name and
operating system

Server name and
operating system

Ser

ver

1, NT

Ser

ver

1, NT

Ser

ver

2, NT

Completing the Application and LUN Planning Worksheet

Application. Enter the application name or type.
File system, partition, or drive. Write the drive letter (for Windows

only) and the partition, file system, logical volume, or drive letter
name, if any.

With a Windows operating system, the LUNs are identified by drive
letter only. The letter does not help you identify the disk
configuration (such as RAID 5). We suggest that later, when you use
the operating system to create a partition on a LUN, you use the disk
administrator software to assign a volume label that describes the
RAID configuration. For example, for drive T, assign the volume ID
RAID5_T. The volume label will then identify the drive letter.

Planning Applications, LUNs, and Storage Groups

3-7

Planning File Systems and LUNs with Shared Switched Storage

3

RAID type of LUN. This is the RAID Group type you want for this
partition, file system, or logical volume. The features of RAID types
are explained in Chapter 2. For a RAID 5, RAID 1, RAID 1/0, and
RAID 0 Group, you can create one or more LUNs on the RAID
Group. For other RAID types, you can create only one LUN per RAID
Group.

LUN ID. The LUN ID is a hexadecimal number assigned when you
bind the disks into a LUN. By default, the ID of the first LUN bound
is 0, the second 1, and so on. Each LUN ID must be unique within the
storage system, regardless of its Storage Group or RAID Group.

The maximum number of LUNs supported on one host-bus adapter
depends on the operating system.

Disk space required (Gbytes). Consider the largest amount of disk
space this application will need, then add a factor for growth.

Server hostname and operating system. Enter the server hostname
(or, if you don’t know the name, a short description that identifies the
server) and the operating system name, if you know it.

LUN and Storage Group Planning Worksheet

Use the following worksheet to select the disks that will make up the
LUNs and Storage Groups in the SAN. A shared storage system can
include up to 100 disks, numbered 0 through 99, left to right from the
bottom up.

3-8

EMC Fibre Channel Storage-System Configuration Planning

Planning File Systems and LUNs with Shared Switched Storage

LUN and Storage Group Planning Worksheet

11_0 11_1 11_211_3 11_4 11_5 11_6 11_7 11_811_9

10_0 10_1 10_210_3 10_4 10_5 10_6 10_7 10_810_9

9_0 9_1 9_2 9_3 9_4 9_5 9_6 9_7 9_8 9_9

8_0 8_1 8_2 8_3 8_4 8_5 8_6 8_7 8_8 9_9

7_0 7_1 7_2 7_3 7_4 7_5 7_6 7_7 7_8 7_9

6_0 6_1 6_2 6_3 6_4 6_5 6_6 6_7 6_8 6_9

5_0 5_1 5_2 5_3 5_4 5_5 5_6 5_7 5_8 5_9

4_0 4_1 4_2 4_3 4_4 4_5 4_6 4_7 4_8 4_9

3_0 3_1 3_2 3_3 3_4 3_5 3_6 3_7 3_8 3_9

2_0 2_1 2_2 2_3 2_4 2_5 2_6 2_7 2_8 2_9

3

1_0 1_1 1_2 1_3 1_4 1_5 1_6 1_7 1_8 1_9

0_0 0_1 0_2 0_3 0_4 0_5 0_6 0_7 0_8 0_9

Storage system number or name:_______________
Storage Group ID or name:______ Server hostname:_____________________ Dedicated Shared
LUN ID or name_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________
LUN ID or name_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________
LUN ID or name_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________
LUN ID or name_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________

Storage Group ID or name:______ Server hostname:_____________________ Dedicated Shared
LUN ID or name_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________
LUN ID or name_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________
LUN ID or name_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________
LUN ID or name_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________

Storage Group ID or name:______ Server hostname:_____________________ Dedicated Shared
LUN ID or name_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________
LUN ID or name_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________
LUN ID or name_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________
LUN ID or name_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________

Planning Applications, LUNs, and Storage Groups

3-9

Planning File Systems and LUNs with Shared Switched Storage

_
_
_
_

_
_
_
_

3

Part of a sample LUN and Storage Group worksheet follows.

3_0 3_1 3_2 3_3 3_4 3_5 3_6 3_7 3_8 3_9

2_0 2_1 2_2 2_3 2_4 2_5 2_6 2_7 2_8 2_9

LUN 2

RAID 1

LUN 0

RAID 5

Storage system number or name:_______________
Storage Group ID or name:______ Server hostname:_____________________ Dedicated Shared
LUN ID or name_______RAID type ___ Cap. (Gb) _____ Disk IDs_____________________________
LUN ID or name_______RAID type ___ Cap. (Gb) _____ Disk IDs_____________________________
LUN ID or name_______RAID type ___ Cap. (Gb) _____ Disk IDs_____________________________
LUN ID or name_______RAID type ___ Cap. (Gb) _____ Disk IDs_____________________________

Storage Group ID or name:______ Server hostname:_____________________ Dedicated Shared
LUN ID or name_______RAID type ___ Cap. (Gb) _____ Disk IDs_____________________________
LUN ID or name_______RAID type ___ Cap. (Gb) _____ Disk IDs_____________________________
LUN ID or name_______RAID type ___ Cap. (Gb) _____ Disk IDs_____________________________
LUN ID or name_______RAID type ___ Cap. (Gb) _____ Disk IDs_____________________________

0

1

2

1_0 1_1 1_2 1_3 1_4 1_5 1_6 1_7 1_8 1_9

0_0 0_1 0_2 0_3 0_4 0_5 0_6 0_7 0_8 0_9

SS1

Mail 1

5

5

Index1

1

72

72

Server2

18

Server1

LUN 1

RAID 5

X

0_0, 0_1, 0_2, 0_3, 0_4

0_5, 0_6, 0_7, 0_8, 0_9

X

1_0, 1_1

Completing the LUN and Storage Group Planning Worksheet

As shown, draw circles around the disks that will compose each
LUN, and within each circle specify the RAID type (for example,
RAID 5) and LUN ID. This is information you will use to bind the
disks into LUNs. For disk IDs, use the form shown. This form is
enclosure_diskID, where enclosure is the enclosure number (the bottom
one is 0, above it 1, and so on) and diskID is the disk position (left is 0,
next is 1, and so on).

3-10

None of the disks 0_0 through 0_8 may be used as a hot spare.

Next, complete as many of the Storage System sections as needed for
all the Storage Groups in the SAN. Copy the (blank) worksheet as
needed for all Storage Groups in each storage system.

A storage system is any group of enclosures connected to a DPE; it
can include up to 11 DAE enclosures for a total of 120 disks. If a

EMC Fibre Channel Storage-System Configuration Planning

LUN Details Worksheet

Planning File Systems and LUNs with Shared Switched Storage

3

Storage Group will be dedicated (not accessible by another system in
a cluster), mark the Dedicated box at the end of its line; if the Storage
Group will be accessible to one or more other servers in a cluster,
write the hostnames of all servers and mark the Shared box.

Use the following LUN details worksheet to plan the individual
LUNs. Complete as many of these as needed for all LUNs in your
SAN.

Planning Applications, LUNs, and Storage Groups

3-11

Planning File Systems and LUNs with Shared Switched Storage

3

LUN Details Worksheet

Storage system (complete this section once for each storage system)

Storage-system number or name:______
Storage-system installation type
❏ Unshared Direct ❏ Shared-or-Clustered Direct ❏ Shared Switched

SP FC-AL address ID (unshared only): SP A:_____SP B:_____

SP memory (Mbytes): SP A:___ SP B:____

❏Use for caching Read cache size:__ MB Write cache size: __ MB Cache page size:___KB

❏ Use for RAID 3

LUN ID:_____

RAID Group ID: Size,GB: LUN size,GB: Disk IDs: SP: ❏ A ❏ B
RAID type: ❏ RAID 5 ❏ RAID 3 - Memory, MB:___ ❏ RAID 1 mirrored pair ❏ RAID 0

Caching: ❏Read and write ❏ Write ❏Read ❏ None

Servers that can access this LUN:

Operating system information: Device name: File system, partition, or drive:

RAID Group ID: Size,GB: LUN size,GB: Disk IDs: SP: ❏A ❏ B
RAID type: ❏ RAID 5 ❏ RAID 3 - Memory, MB:___ ❏ RAID 1 mirrored pair ❏ RAID 0

Caching: ❏Read and write ❏ Write ❏Read ❏ None

❏ RAID 1/0 ❏ Individual disk ❏ Hot spare

LUN ID:____

❏ RAID 1/0 ❏ Individual disk ❏ Hot spare

3-12

Servers that can access this LUN:

Operating system information: Device name: File system, partition, or drive:

LUN ID:____

RAID Group ID: Size,GB: LUN size,GB: Disk IDs: SP: ❏A ❏ B
RAID type: ❏ RAID 5 ❏ RAID 3 - Memory, MB:___ ❏ RAID 1 mirrored pair ❏ RAID 0

❏ RAID 1/0 ❏ Individual disk ❏ Hot spare

Caching: ❏Read and write ❏ Write ❏Read ❏ None

Servers that can access this LUN:

Operating system information: Device name: File system, partition, or drive:

EMC Fibre Channel Storage-System Configuration Planning

Planning File Systems and LUNs with Shared Switched Storage

LUN Details Worksheet

Storage system (complete this section once for each storage system)

Storage-system number or name:__SS1____
Storage-system installation type
❏ Unshared Direct ❏ Shared-or-Clustered Direct ❏ Shared Switched

SP FC-AL address ID (unshared only): SP A:_____SP B:_____

SP memory (Mbytes): SP A:_256__ SP B:_256__

❏ Use for caching Read cache size:_80_ MB Write cache size: _160_ MB Cache page size:_

❏ Use for RAID 3

RAID Group ID: 0 Size,GB: 72 LUN size,GB: 72 Disk IDs: SP: ❏ A ❏ B
RAID type: ❏ RAID 5 ❏ RAID 3 - Memory, MB:___ ❏ RAID 1 mirrored pair ❏ RAID 0

Caching: ❏Read and write ❏Write ❏Read ❏ None

Servers that can access this LUN:

Operating system information: Device name: File system, partition, or drive: T

X

❏ RAID 1/0 ❏ Individual disk ❏ Hot spare

X

Server1

X

LUN ID:__

0___

0_0,0_1,0_2,0_3,0_4

2__KB

X

3

LUN ID:__1__

RAID Group ID: 1 Size,GB: 72 LUN size,GB: 72 Disk IDs: SP: ❏ A ❏B
RAID type: ❏ RAID 5 ❏ RAID 3 - Memory, MB:___ ❏ RAID 1 mirrored pair ❏ RAID 0

Caching: ❏Read and write ❏Write ❏Read ❏ None

Servers that can access this LUN: Server1

Operating system information: Device name: File system, partition, or drive: U

RAID Group ID: 2 Size, GB: LUN size,GB: 18 Disk IDs: SP: ❏ A ❏B
RAID type: ❏ RAID 5 ❏ RAID 3 - Memory, MB:___ ❏ RAID 1 mirrored pair ❏ RAID 0

Caching: ❏Read and write ❏Write ❏Read ❏ None

Servers that can access this LUN:

Operating system information: Device name: File system, partition, or drive: V

X

❏ RAID 1/0 ❏ Individual disk ❏ Hot spare

X

LUN ID:__2__

18

X

❏ RAID 1/0 ❏ Individual disk ❏ Hot spare

Server1

Planning Applications, LUNs, and Storage Groups

0_5, 0_6, 0_7, 0_8, 0_9

1_0, 1_1

X

X

X

3-13

Planning File Systems and LUNs with Shared Switched Storage

3

Completing the LUN Details Worksheet

Complete the header portion of the worksheet for each storage
system as described below. Copy the blank worksheet as needed.

Storage-system entries

Storage-system installation type, specify Shared Switched
storage.

SP FC-AL address ID. This does not apply to shared storage, in
which the switch determines the address of each device.

Use memory for caching. You can use SP memory for read/write
caching or RAID 3. (Using both caching and RAID 3 in the same
storage system is not recommended.) You can use different cache
settings for different times of day (for example, for user I/O
during the day, use more write cache; for sequential batch jobs at
night, use more read cache. You enable caching for specific LUNs
— allowing you to tailor your cache resources according to
priority. If you choose caching, check the box and continue to the
next step; for RAID 3, skip to the RAID Group ID entry.

Read cache size. If you want a read cache, it should generally be
about one third of the total available cache memory.

3-14

Write cache size. The write cache should be two thirds of the total
available. Some memory is required for system overhead, so you
cannot determine a precise figure at this time. For example, for
256 Mbytes of total memory, you might have 240 Mbytes
available, and you would specify 80 Mbytes for the read cache
and 160 Mbytes for the write cache.

Cache page size. This applies to both read and write caches. It can
be 2, 4, 8, or 16 Kbytes. As a general guideline, we suggest

• For a general-purpose file server — 8 Kbytes

• For a database application — 2 or 4 Kbytes

The ideal cache page size depends on the operating system and
application.

Use memory for RAID 3. If you want to use the SP memory for
RAID 3, check the box.

RAID Group/LUN Entries

Complete a RAID Group/LUN entry for each LUN and hot spare.

EMC Fibre Channel Storage-System Configuration Planning

Planning File Systems and LUNs with Shared Switched Storage

LUN ID. The LUN ID is a hexadecimal number assigned when
you bind the disks into a LUN. By default, the ID of the first LUN
bound is 0, the second 1, and so on. Each LUN ID must be unique
within the storage system, regardless of its Storage Group or
RAID Group.

The maximum number of LUNs supported on one host-bus
adapter depends on the operating system.

RAID Group ID. This ID is a hexadecimal number assigned
when you create the RAID Group. By default, the number of the
first RAID Group in a storage system is 0, the second 1, and so on,
up to the maximum of 1F (31).

Size (RAID Group size). Enter the user-available capacity in
gigabytes (Gbytes) of the whole RAID Group. You can determine
the capacity as follows:

RAID5 or RAID-3 Group: disk-size * (number-of-disks - 1)
RAID 1/0 or RAID-1 Group: (disk-size * number-of-disks) / 2
RAID 0 Group: disk-size * number-of-disks
Individual unit: disk-size

3

For example,

• A five-disk RAID 5 or RAID 3 Group of 36-Gbyte disks holds
144 Gbytes;

• An eight-disk RAID 1/0 Group of 36-Gbyte disks also holds
144 Gbytes;

• A RAID 1 mirrored pair of 36-Gbyte disks holds 36 Gbytes;
and

• An individual disk of an 36-Gbyte disk also holds 36 Gbytes.

Each disk in the RAID Group must have the same capacity;
otherwise, you will waste disk storage space.

LUN size. Enter the user-available capacity in gigabytes (Gbytes)
of the LUN. You can make this the same size as the RAID Group,
above. Or, for a RAID 5, RAID 1, RAID 1/0, or RAID 0 Group,
you can make the LUN smaller than the RAID Group. You might
do this if you wanted a RAID 5 Group with a large capacity and
wanted to place many smaller capacity LUNs on it; for example,
to specify a LUN for each user. However, having multiple LUNs

Planning Applications, LUNs, and Storage Groups

3-15

Planning File Systems and LUNs with Shared Switched Storage

3

per RAID Group may adversely impact performance. If you want
multiple LUNs per RAID Group, then use a RAID Group/LUN
series of entries for each LUN.

Disk IDs. Enter the ID(s) of all disks that will make up the LUN
or hot spare. These are the same disk IDs you specified on the
previous worksheet. For example, for a RAID 5 Group in the DPE
(enclosure 0, disks 2 through 6), enter 0_2, 0_3, 0_4, 0_5, and 0_6.

SP. Specify the SP that will own the LUN: SP A or SP B. You can
let the management program automatically select the SP to
balance the workload between SPs; to do so, leave this entry
blank.

RAID type. Copy the RAID type from the previous worksheet.
For example, RAID 5 or hot spare. For a hot spare (not strictly
speaking a LUN at all), skip the rest of this LUN entry and
continue to the next LUN entry (if any).

If this is a RAID 3 Group, specify the amount of SP memory for
that group. To work efficiently, each RAID 3 Group needs at least
6 Mbytes of memory.

Caching. If you want to use caching (entry on page 3-14), you can
specify whether you want caching — read and write, read, or
write for this LUN. Generally, write caching improves
performance far more than read caching. The ability to specify
caching on a LUN basis provides additional flexibility, since you
can use caching for only the units that will benefit from it. Read
and write caching recommendations follow.

3-16

Table 3-1 Cache Recommendations for Different RAID Types

RAID 5 RAID 3 RAID 1 RAID 1/0 RAID 0 Individual Unit

Highly Recommended Not allowed Recommended Recommended Recommended Recommended

Servers that can access this LUN. Enter the name of each server
(copied from the LUN and Storage Group worksheet).

Operating system information: Device name. Enter the
operating system device name, if this is important and if you
know it. Depending on your operating system, you may not be
able to complete this field now.

EMC Fibre Channel Storage-System Configuration Planning

Planning File Systems and LUNs with Shared Switched Storage

File system, partition, or drive. Write the name of the file system,
partition, or drive letter you will create on this LUN. This is the
same name you wrote on the application worksheet.

On the following line, write any pertinent notes; for example, the
file system mount- or graft-point directory pathname (from the
root directory). If this storage system’s chassis will be shared with
another server, and the other server is the primary owner of this
disk, write secondary. (As mentioned earlier, if the storage system
will be used by two servers, we suggest you complete one of
these worksheets for each server.)

What Next? This chapter outlined the planning tasks for shared storage systems.

If you have completed the worksheets to your satisfaction, you are
ready to learn about the hardware needed for these systems as
explained in Chapter 5.

3

Planning Applications, LUNs, and Storage Groups

3-17

Planning File Systems and LUNs with Shared Switched Storage

3

3-18

EMC Fibre Channel Storage-System Configuration Planning

Invisible Body Tag

4

Planning LUNs and File

Systems with Unshared

Direct Storage

This chapter shows sample RAID and LUN configurations with
direct storage installations and then provides worksheets for
planning your own storage installation. Topics are

• Dual SPs and Paths to LUNs............................................................4-2

• Unshared Direct and Shared-or-Clustered Direct Storage...........4-2

• Planning Applications and LUNs ...................................................4-4

Planning LUNs and File Systems with Unshared Direct Storage

4-1

Planning LUNs and File Systems with Unshared Direct Storage

4

Dual SPs and Paths to LUNs

If a storage system has two SPs, there are two routes to its LUNs. If
the server has two adapters and the storage system has two SPs,
Application Transparent Failover (ATF). ATF can automatically
switch to the other path, without disrupting applications, if a device
(such as a host-bus adapter, cable, or SP) fails.

Unshared Direct and Shared-or-Clustered Direct Storage

This section explains the direct (unswitched) options available for
connecting storage systems to servers. As needs change, you may
want to change a configuration. You can do so without changing your
LUN configuration or losing user data.

There are two types of installation:

• Unshared direct with one server is the simplest and least costly;

• Shared-or-clustered direct lets two clustered servers share

storage resources with high availability.

Sample Unshared Direct Installation

Disk IDs

100-109

010-019

Figure 4-1 Unshared Direct Installation

4-2

EMC Fibre Channel Storage Systems Configuration Planning Guide

Server

Adapter

Adapter

SP A SP B

Database
RAID 5

Sys
RAID 1

Users
RAID 5

Clients, mail
RAID 5

Path
Path 2

1

EMC1825

Planning LUNs and File Systems with Unshared Direct Storage

The storage system disk IDs and LUNs are as follows. The LUN
capacities shown assume 36-Gbyte disks.

LUNs - SP A and SP B, 422 Gbytes

4

Disk IDs

RAID type, storage type, capacity

0_0, 0_1 RAID 1, System disk, 36 Gbytes
0_2-0_9 RAID 5 (8 disks), Clients and Mail, 216 Gbytes
1_0-1_4 RAID 5, Database, 144 Gbytes
1_5 Disk, Temporary storage, 36 Gbytes

Sample Shared-or-Clustered Direct Installation

Server 1 (S1)

Adapter

Adapter

S

P A

S2 Customers
RAID 5

Storage
system

Figure 4-2 Sample Clustered Installation

S1Mail

RAID1

Spare

Server 2 (S2)

Adapter

S1Dbase
RAID 5

SP B

Unused

RAID1

Adapter

S2 Usri

Path 1
Path 2

If each disk holds 36 Gbytes, then the storage-system chassis provides
Server 1 with 256 Gbytes of disk storage, 220 Gbytes highly available;
it provides Server 2 with 216 Gbytes of storage, all highly available.
Each server has its own SP, which controls that server’s LUNs; those
LUNs remain primary to that server. The LUNs are as follows.

Server1 LUNs (S1) - SP A, 256 Gbytes Server2 LUNs (S2) - SP B, 216 Gbytes

RAID type, storage type, capacity

Disk IDs
0_0, 0_1 RAID 1, System disk, 36 Gbytes

0_2 Disk, Temporary storage, 36 Gbytes
0_3-0_7 RAID 5, Database, 144 Gbytes
0_8-0_ 9 RAID 1, Users, 36 Gbytes

Unshared Direct and Shared-or-Clustered Direct Storage

RAID type, storage type, capacity

Disk IDs
1_0-1_7 RAID 5 (8 disks), Cust Accounts, 216

Gbytes

4-3

Planning LUNs and File Systems with Unshared Direct Storage

4

Planning Applications and LUNs

This section helps you plan your unshared (direct) storage use —
applications you want to run and the LUNs that will hold them. The
worksheets to help you do this include

• Application and file system planning worksheet - lets you outline
your storage needs.

• LUN planning worksheet - lets you decide on the disks that will
compose the LUNs.

• LUN details worksheet - lets you plan each LUN in detail.

Make as many copies of each blank worksheet as you need. You will
need this information later when you configure the shared storage
system.

Sample file system, Storage Group, and LUN worksheets appear later
in this chapter.

Application and LUN Planning

4-4

Use the following worksheet to plan your file systems and RAID
types. For each application, write the application name, file system (if
any), RAID type, LUN ID (ascending integers, starting with 0), disk
space required, and finally the name of the servers and operating
systems that will use the LUN.

EMC Fibre Channel Storage Systems Configuration Planning Guide

Application and LUN Planning Worksheet

Planning LUNs and File Systems with Unshared Direct Storage

4

RAID type of

Application File system (if any)

LUN

A sample worksheet begins as follows:

Application File system (if any)

a

il 1 RAI D 5 0

M

Mail 2 RAI D 5 1

Database index RAI

RAID type of
LUN

D 1 2

LUN
ID (hex)

LUN
ID (hex)

Disk space
required
(Gbytes)

Disk space
required
(Gbytes)

72 G

b

72 G

b

18 G

b

Server name and
operating system

Server name and
operating system

Ser

ver

1, NT

Ser

ver

1, NT

Ser

ver

2, NT

Completing the Application and LUN Planning Worksheet

Application. Enter the application name or type.
File system, partition, or drive. Write the drive letter (for Windows

only) and the partition, file system, logical volume, or drive letter
(Windows only) name.

With a system such as Windows NT, the LUNs are identified by drive
letter only. The letter does not help you identify the disk
configuration (such as RAID 5). We suggest that later, when you use
the operating system to create a partition on the unit, you use the disk
administrator software to assign a volume label that describes the

Planning Applications and LUNs

4-5

Planning LUNs and File Systems with Unshared Direct Storage

4

RAID configuration. For example, for drive T, assign the volume ID

RAID5_T. The volume label will then identify the drive letter.
RAID type of LUN is the RAID Group type you want for this

partition, file system, or logical volume. The features of RAID types
are explained in Chapter 2. For a RAID 5, RAID 1, RAID 1/0, and
RAID 0 Group, you can create one or more LUNs on the RAID
Group. For other RAID types, you can create only one LUN per RAID
Group.

LUN ID is a hexadecimal number assigned when you bind the disks
into a LUN. By default, the ID of the first LUN bound is 0, the second
1, and so on. Each LUN ID must be unique within the storage system,
regardless of its Storage Group or RAID Group.

The maximum number of LUNs supported on one host-bus adapter
depends on the operating system. Some systems allow only eight
LUNs (numbers 0 through 7). For an operating system with this
restriction, if you want a hot spare, assign the hot spare an ID above
7; for example, 8 or 9. The operating system never accesses a hot
spare, so the ID is irrelevant to it.

Disk space required (Gbytes), Consider the largest amount of disk
space this application will need, then add a factor for growth.

LUN Planning Worksheet

4-6

EMC Fibre Channel Storage Systems Configuration Planning Guide

Server hostname and operating system Enter the server hostname
(or, if you don’t know the name, a short description that identifies the
server) and the operating system name, if you know it.

If this storage system will be used by two servers, provide a copy of
this worksheet to the other server. This is particularly important
where one server may take over the other’s LUNs. If a LUN will be
shared, on the Notes section of the LUN details worksheet, write
Primary to server-name or Secondary to server-name.

Use one of the following worksheets (Rackmount or Deskside) to
select the disks that will make up the LUNs. Depending on model, a
full-fibre rackmount storage system can include up to 100 disks,
numbered 0 through 99, left to right from the bottom up.

Again depending on model, a deskside storage system can hold ten,
20, or 30 disks.

Planning LUNs and File Systems with Unshared Direct Storage

LUN Planning Worksheet - Rackmount

Full-fibre storage system

11_0 11_1 11_2 11_3 11_4 11_5 11_6 11_7 11_8 11_9

10_0 10_1 10_2 10_3 10_4 10_5 10_6 10_7 10_8 10_9

9_0 9_1 9_2 9_3 9_4 9_5 9_6 9_7 9_8 9_9

8_0 8_1 8_2 8_3 8_4 8_5 8_6 8_7 8_8 8_9

7_0 7_1 7_2 7_3 7_4 7_5 7_6 7_7 7_8 7_9

6_0 6_1 6_2 6_3 6_4 6_5 6_6 6_7 6_8 6_9

5_0 5_1 5_2 5_3 5_4 5_5 5_6 5_7 5_8 5_9

4_0 4_1 4_2 4_3 4_4 4_5 4_6 4_7 4_8 4_9

3_0 3_1 3_2 3_3 3_4 3_5 3_6 3_7 3_8 3_9

4

2_0 2_1 2_2 2_3 2_4 2_5 2_6 2_7 2_8 2_9

1_0 1_1 1_2 1_3 1_4 1_5 1_6 1_7 1_8 1_9

0_0 0_1 0_2 0_3 0_4 0_5 0_6 0_7 0_8 0_9

LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________
LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________
LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________
LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________

LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________
LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________
LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________
LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________

Planning Applications and LUNs

4-7

Planning LUNs and File Systems with Unshared Direct Storage

_
_
_
_

_
_
_
_

4

LUN Planning Worksheet - Deskside

Full-fibre storage system

0_0

0_1

0_2

0_3

0_4

0_5

0_6

0_7

0_8

0_9

1_0

1_1

1_2

1_3

1_4

1_5

1_6

1_7

1_8

1_9

2_0

2_1

2_2

2_3

2_4

2_5

2_6

2_7

2_8

2_9

Storage system number_____
LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_______________________________________
LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_______________________________________
LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_______________________________________
LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_______________________________________

LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_______________________________________
LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_______________________________________
LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_______________________________________
LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_______________________________________

4-8

EMC Fibre Channel Storage Systems Configuration Planning Guide

Planning LUNs and File Systems with Unshared Direct Storage

A sample LUN worksheet follows.

2_0 2_1 2_2 2_3 2_4 2_5 2_6 2_7 2_8 2_9

4

LUN 2

1_0 1_1 1_2 1_3 1_4 1_5 1_6 1_7 1_8 1_9

RAID 1

LUN 0

0_0 0_1 0_2 0_3 0_4 0_5 0_6 0_7 0_8 0_9

RAID 5

LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________
LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________
LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________
LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________

LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________
LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________
LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________
LUN number_______RAID type ___ Cap. (Gb) _____ Disk IDs_________________________________________

0

1

2

Completing the LUN Planning Worksheet

As shown, draw circles around the disks that will compose each
LUN, and within each circle specify the RAID type (for example,
RAID 5) and LUN ID. This is information you will use to bind the
disks into LUNs. For disk IDs, use the form shown. This form is
enclosure_diskID, where enclosure is the enclosure number (the bottom
one is 0, above it 1, and so on) and diskID is the disk position (left is 0,
next is 1, and so on).

5

1

5

1

144

144

36

LUN 1

RAID 5

0_0, 0_1, 0_2, 0_3, 0_4

0_5, 0_6, 0_7, 0_8, 0_9

1_0, 1_1

None of the disks 0_0 through 0_8 may be used as a hot spare.

Next, complete as many of the LUN sections as needed for each
storage system.Copy the (blank) worksheet as needed for all LUNs in
each storage system. A storage system is any group of enclosures
connected to a DPE; a full-fibre system can include up to nine DAE
enclosures for a total of 100 disks.

LUN Details Worksheet Use the following LUN details worksheet to plan the individual

LUNs. Complete as many of these as needed for all LUNs.

Planning Applications and LUNs

4-9

Planning LUNs and File Systems with Unshared Direct Storage

4

LUN Details Worksheet

Storage system (complete this section once for each storage system)

Storage-system number or name:______
Storage-system installation type
❏ Unshared Direct ❏ Shared-or-Clustered Direct ❏ Shared Switched

SP FC-AL address ID (unshared only): SP A:_____SP B:_____

SP memory (Mbytes): SP A:______ SP B:______

V Use for caching Read cache size:___ MB Write cache size: ___ MB Cache page size:___KB

VUse for RAID 3

LUN ID:_____

RAID Group ID: Size,GB: LUN size,GB: Disk IDs: SP: VA VB
RAID type: VRAID 5 V RAID 3 - Memory, MB:___ V RAID 1 mirrored pair V RAID 0

V RAID 1/0 V Individual disk V Hot spare

Caching: VRead and write VWrite VRead VNone

Servers that can access this LUN:

Operating system information: Device name: File system, partition, or drive:

LUN ID:_____

RAID Group ID: Size,GB: LUN size,GB: Disk IDs: SP: VA VB
RAID type: VRAID 5 V RAID 3 - Memory, MB:___ V RAID 1 mirrored pair V RAID 0

Caching: VRead and write VWrite VRead VNone

V RAID 1/0 V Individual disk V Hot spare

4-10

Servers that can access this LUN:

Operating system information: Device name: File system, partition, or drive:

LUN ID:_____

RAID Group ID: Size,GB: LUN size,GB: Disk IDs: SP: VA VB
RAID type: VRAID 5 V RAID 3 - Memory, MB:___ V RAID 1 mirrored pair V RAID 0

V RAID 1/0 V Individual disk V Hot spare

Caching: VRead and write VWrite VRead VNone

Servers that can access this LUN:

Operating system information: Device name: File system, partition, or drive:

EMC Fibre Channel Storage Systems Configuration Planning Guide

Planning LUNs and File Systems with Unshared Direct Storage

LUN Details Worksheet

Storage system (complete this section once for each storage system)

Storage-system number or name:__1____
Storage-system installation type

X

❏ Unshared Direct ❏ Shared-or-Clustered Direct ❏ Shared Switched

SP FC-AL address ID (unshared only): SP A:_____SP B:_____

SP memory (Mbytes): SP A:_

V Use for caching Read cache size:_

X

VUse for RAID 3

RAID Group ID: 0 Size,GB: 144 LUN size,GB: 144 Disk IDs: SP: VA VB
RAID type: VRAID 5 V RAID 3 - Memory, MB:___ V RAID 1 mirrored pair V RAID 0

Caching: VRead and write VWrite VRead VNone

X

V RAID 1/0 V Individual disk V Hot spare

X

128__ SP B:_128__

40_ MBWrite cache size: _80_ MBCache page size:_2__KB

LUN ID:__

0___

0_0, 0_1, 0_2, 0_3, 0_4

X

4

Servers that can access this LUN:

Operating system information: Device name: File system, partition, or drive: T

RAID Group ID: 1 Size,GB: 144 LUN size,GB: 144 Disk IDs: SP: VA VB
RAID type: VRAID 5 V RAID 3 - Memory, MB:___ V RAID 1 mirrored pair V RAID 0

Caching: VRead and write VWrite VRead VNone

Servers that can access this LUN: Server1

Operating system information: Device name: File system, partition, or drive: U

RAID Group ID: 2 Size,GB: LUN size, GB: 36 Disk IDs: SP: VA VB
RAID type: VRAID 5 V RAID 3 - Memory, MB:___ V RAID 1 mirrored pair V RAID 0

Caching: VRead and write VWrite VRead VNone

Servers that can access this LUN:

Operating system information: Device name: File system, partition, or drive: V

X

V RAID 1/0 V Individual disk V Hot spare

X

18

V RAID 1/0 V Individual disk V Hot spare

X

Server1

Server1

LUN ID:__1__

LUN ID:__2__

0_5, 0_6, 0_7, 0_8, 0_9

1_0, 1_1

X

X

X

Planning Applications and LUNs

4-11

Planning LUNs and File Systems with Unshared Direct Storage

4

Completing the LUN Details Worksheet

Complete the header portion of the worksheet for each storage
system as described below. Copy the blank worksheet as needed.
Sample completed LUN worksheets appear later.

Storage-System Entries

Storage-system configuration. Specify Unshared Direct (one server)
or Shared-or-Clustered Direct (two servers).

For any multiple-server configuration, each server will need cluster
software.

SP FC-AL address ID. For unshared storage, which uses FC-AL
addressing, each SP (and each other node) on a Fibre Channel loop
must have a unique FC-AL address ID. You set the SP FC-AL address
ID using switches on the back panel of the SP. The valid FC-AL
address ID range is a number 0 through 125 decimal, which is 0
through 7D hexadecimal. For any number above 9, we suggest
hexadecimal, since the switches are marked in hexadecimal.

If you have two FC-AL loops, we suggest a unique FC-AL address ID
for each SP on both loops.

4-12

SP memory. Enter the amount of memory each SP has. If a storage
system has two SPs, they will generally have the same amount of
memory. You can allocate this memory to storage-system caching or
RAID 3 use.

Use memory for caching. You can use SP memory for read/write
caching or RAID 3. (Using both caching and RAID 3 in the same
storage system not recommended.) You can use different cache
settings for different times of day (for example, for user I/O during
the day, use more write cache; for sequential batch jobs at night, use
more read cache. You enable caching for specific LUNs — allowing
you to tailor your cache resources according to priority. If you choose
caching, check the box and continue to the next step; for RAID 3, skip
to the RAID Group ID entry.

Read cache size. If you want a read cache, it should generally be
about one third of the total available cache memory.

Write cache size. The write cache should be two thirds of the total
available. Some memory is required for system overhead, so you
cannot determine a precise figure at this time. For example, for 256
Mbytes of total memory, you might have 240 Mbytes available, and

EMC Fibre Channel Storage Systems Configuration Planning Guide

Planning LUNs and File Systems with Unshared Direct Storage

you would specify 80 Mbytes for the read cache and 160 Mbytes for
the write cache.

Cache page size. This applies to both read and write caches. It can be
2, 4, 8, or 16 Kbytes. As a general guideline, we suggest

For a general-purpose file server — 8 Kbytes
For a database application — 2 or 4 Kbytes
The ideal cache page size depends on the operating system and

application.
Use memory for RAID 3. If you want to use the SP memory for

RAID 3, check the box.

RAID Group/LUN Entries

Complete a RAID Group/LUN entry for each LUN and hot spare.
LUN ID. The LUN ID is a hexadecimal number assigned when you

bind the disks into a LUN. By default, the ID of the first LUN bound
is 0, the second 1, and so on. Each LUN ID must be unique within the
storage system, regardless of its Storage Group or RAID Group.

The maximum number of LUNs supported on one host-bus adapter
depends on the operating system. Some systems allow only eight
LUNs (numbers 0 through 7). For an operating system with this
restriction, if you want a hot spare, assign the hot spare an ID above
7; for example, 8 or 9. The operating system never accesses a hot
spare, so the ID is irrelevant to it.

4

RAID Group ID. This is a hexadecimal number assigned when you
create the RAID Group. By default, the number of the first RAID
Group in a storage system is 0, the second 1, and so on, up to the
maximum of 1F (31).

Size (RAID Group size) Enter the user-available capacity in gigabytes
(Gbytes) of the whole RAID Group. You can determine the capacity
as follows:

RAID-5 or RAID-3 Group: disk-size * (number-of-disks - 1)
RAID 1/0 or RAID-1

(disk-size * number-of-disks) / 2

Group:
RAID-0 Group: disk-size * number-of-disks
Individual unit: disk-size

Planning Applications and LUNs

4-13

Planning LUNs and File Systems with Unshared Direct Storage

4

For example,

• A five-disk RAID 5 or RAID 3 Group of 36-Gbyte disks holds
144 Gbytes;

• An eight-disk RAID 1/0 Group of 36-Gbyte disks also holds
144Gbytes;

• A RAID 1 mirrored pair of 36-Gbyte disks holds 36 Gbytes; and

• An individual disk of a 36-Gbyte disk also holds 36 Gbytes.

Each disk in the RAID Group must have the same capacity;
otherwise, you will waste disk storage space.

LUN Size. Enter the user-available capacity in gigabytes (Gbytes) of
the LUN. You can make this the same size as the RAID Group, above.
Or, for a RAID 5, RAID 1, RAID 1/0, or RAID 0 Group, you can make
the LUN smaller than the RAID Group. You might do this if you
wanted a RAID 5 Group with a large capacity and wanted to place
many smaller capacity LUNs on it; for example, to specify a LUN for
each user. However, having multiple LUNs per RAID Group may
adversely impact performance. If you want multiple LUNs per RAID
Group, then use a RAID Group/LUN series of entries for each LUN.

4-14

Disk IDs. Enter the ID(s) of all disks that will make up the LUN or
hot spare. These are the same disk IDs you specified on the previous
worksheet. For example, for a RAID-5 Group in the DPE (enclosure 0,
disks 2 through 6), enter 0_2, 0_3, 0_4, 0_5, and 0_6.

SP. Specify the SP that will own the LUN: SP A or SP B. You can let
the management program automatically select the SP to balance the
workload between SPs; to do so, leave this entry blank.

RAID type. Copy the RAID type from the previous worksheet. For
example, RAID 5 or hot spare. For a hot spare (not strictly speaking a
LUN at all), skip the rest of this LUN entry and continue to the next
LUN entry (if any).

If this is a RAID 3 Group, specify the amount of SP memory for that
group. To work efficiently, each RAID 3 Group needs at least
6Mbytes of memory.

Caching. If you want to use caching (entry on page 4-12), you can
specify whether you want caching — read and write, read, or write
for this LUN. Generally, write caching improves performance far
more than read caching. The ability to specify caching on a LUN basis
provides additional flexibility, since you can use caching for only the

EMC Fibre Channel Storage Systems Configuration Planning Guide

Planning LUNs and File Systems with Unshared Direct Storage

units that will benefit from it. Read and write caching
recommendations follow.

Table 4-1 Cache Recommendations for Different RAID Types

RAID 5 RAID 3 RAID 1 RAID 1/0 RAID 0 Individual Unit

Highly Recommended Not allowed Recommended Recommended Recommended Recommended

Servers that can access this LUN. Enter the name of each server that
will be able to use the LUN. Normally, you need to restrict access by
establishing SP ownership of LUNs when you bind them.

Operating system information: Device name. Enter the operating
system device name, if this is important and if you know it.
Depending on your operating system, you may not be able to
complete this field now.

File system, partition, or drive. Write the name of the file system,
partition, or drive letter you will create on this LUN. This is the same
name you wrote on the application worksheet.

On the following line, write any pertinent notes; for example, the file
system mount- or graft-point directory pathname (from the root
directory). If this storage system’s chassis will be shared with another
server, and the other server is the primary owner of this disk, write
secondary. (If the storage system will be used by two servers, we
suggest you complete one of these worksheets for each server.)

4

What Next? This chapter outlined the planning tasks for unshared storage

systems. If you have completed the worksheets to your satisfaction,
you are ready to learn about the hardware needed for these systems
as explained in Chapter 5.

Planning Applications and LUNs

4-15

Planning LUNs and File Systems with Unshared Direct Storage

4

4-16

EMC Fibre Channel Storage Systems Configuration Planning Guide

Invisible Body Tag

5

Storage System

Hardware

This chapter describes the storage-system hardware components.
Topi cs are

• Hardware for Shared Storage...........................................................5-3

• Hardware for Unshared Storage......................................................5-6

• Planning Your Hardware Components........................................ 5-11

• Hardware Data Sheets.....................................................................5-14

• Cabinets for Rackmount Enclosures .............................................5-20

• Cable and Configuration Guidelines ............................................5-21

• Hardware Planning Worksheets ....................................................5-24

Storage System Hardware

5-1

Storage System Hardware

5

The storage systems attach to the server and the interconnect
components described in Chapter 1.

Server
component

Interconnect

component

Storage
component

Unshared Direct

(one server)

Server

Adapter

Adapter

FC loop 1
FC loop 2

Figure 5-1 Shared and Unshared Storage

Shared-or-Clustered Direct

(two servers)

Server

Adapter

Disk-array storage systems

Server

Adapter

Adapter

Adapter

Shared Switched

(multiple servers)

Server

Adapter

Switch fabric Switch fabric

Server

Adapter

Adapter

Adapter

Server

Adapter

Adapter

5-2

EMC Fibre Channel Storage Systems Configuration Planning Guide

Hardware for Shared Storage

The primary hardware component for shared storage is a ten-slot
Disk-array Processor Enclosure (DPE) with two storage processors
(SP). The DPE can support up to nine separate 10-slot enclosures
called Disk Array Enclosures (DAEs) for a total of 100 disks. Shared
storage requires two SPs and the Access Logix software option.

A DPE with a DAE is available as a deskside system, but with a
capacity of 20 disks this cannot provide the expandability and total
storage capacity needed for a SAN (storage area network). So this
section does not cover the deskside version.

Storage Hardware — Rackmount DPE-Based Storage Systems

The DPE rackmount enclosure is a sheet-metal housing with a front
door, a midplane, and slots for the storage processors (SPs), link
control cards (LCCs), disk modules, power supplies, and fan packs.
All components can be replaced under power. The DPE rackmount
model looks like the following figure.

Storage System Hardware

5

Front

Link control
card (LCC)

Disk modules (front door
removed for clarity)

Figure 5-2 DPE Storage-System Components – Rackmount Model

Storage processors (SPs)

Back

FC ports with GBICs

A separate standby power supply (SPS) is required to support write
caching. All the shared storage components — rackmount DPE,
DAEs, SPSs, and cabinet — are shown in the following figure.

Hardware for Shared Storage

Power supplies

LCC

Drive fan module
(detached for clarity)

5-3

Storage System Hardware

5

Disks

DAE

DAE

DPE

Standby power
supplies (SPSs)

Figure 5-3 Rackmount System with DPE and DAEs

DAE

DAE

DPE

SPs

Front

Rear

EMC1744

The disks — available in differing capacities — fit into slots in the
enclosure. Each module has a unique ID that you use when binding
or monitoring its operation. The ID is derived from the enclosure
address (always 0 for the DPE, settable on a DAE) and the disk
module slot numbers.

5-4

EMC Fibre Channel Storage Systems Configuration Planning Guide

Storage Processor (SP)

Storage System Hardware

Disk Modules and Module IDs — Rackmount DPE-Based System

10 11 12 13 14 15 16 17 18 19

0

1 2

3

4 5

6 7

8

9

The SP provides the intelligence of the storage system. Using its own
operating system (called Core Software), the SP processes the data
written to or read from the disk modules, and monitors the modules
themselves. An SP consists of a printed-circuit board with memory
modules (DIMMs), and status lights.

5

For high availability, a storage system can support a second SP. The
second SP provides a second route to a storage system and also lets
the storage system use write caching for enhanced write
performance. Two SPs are required for shared storage.

Server Server

Adapter

Adapter

Storage systems

Figure 5-4 Shared Storage Systems

Adapter

Switch fabric

SP A

See Chapter 3 for more examples of shared storage.

Adapter

SP B

Server

Adapter

Adapter

Switch fabric

SP A SP B

Path 1

Path 2

Hardware for Shared Storage

5-5

Storage System Hardware

5

Hardware for Unshared Storage

Unshared storage systems are less costly and less complex than
shared storage systems. They offer many shared storage system
features; for example, you can use multiple unshared storage systems
with multiple servers. However, with multiple servers, unshared
storage offers less flexibility and security than shared storage, since
any user with write access to privileged server files can enable access
to any storage system.

Types of Storage System for Unshared Storage

For unshared storage, there are four types of storage system, each
using the FC-AL protocol. Each type is available in a rackmount or
deskside (office) version.

• Disk-array Processor Enclosure (DPE) storage systems. A DPE is
a 10-slot enclosure with hardware RAID features provided by one
or two storage processors (SPs). In addition to its own disks, a
DPE can support up to 110 additional disks in 10-slot Disk Array
Enclosures (DAEs) for a total of 120 disks. This is the same kind of
storage system used for shared storage, but it uses a different
storage processor (SP).

5-6

• Intelligent Disk Array Enclosure (iDAE). An iDAE, like a DPE,
has SPs and thus all the features of a DPE, but is thinner and has a
limit of 30 disks.

• Disk Array Enclosure (DAE). A DAE does not have SPs. A DAE
can connect to a DPE or an iDAE, or you can use it without SPs. A
DAE used without an SP does not inherently include RAID, but
can operate as a RAID device using software running on the
server system. Such a DAE is also known as Just a Box of Disks, or
JBOD.

EMC Fibre Channel Storage Systems Configuration Planning Guide

Disk-array processor enclosure (DPE)

Storage System Hardware

5

Deskside DPE with DAE

Rackmount DPE, one enclosure,
supports up to 9 DAEs

Intelligent disk-array enclosure (iDAE)

30-slot deskside Rackmount10-slot deskside

Figure 5-5 Storage System Types for Unshared Storage

Hardware for Unshared Storage

5-7

Storage System Hardware

5

The following figure shows some components of a deskside DPE.
Components for rackmount types are similar.

DPE

SP fan cover
(covers SP
fan pack)

Front

DAE link control
card (LCC)

DPE LCC

DAE power supplies

DPE power supplies

DAE

Front doors
(cover disk modules)

Figure 5-6 DPE Components - Deskside Model

Back (fans and cables
omitted for clarity)

Power distribution
units

Storage processors
(SPs)

DPE LCC

DAE LCC

FC ports

SPS units

5-8

Disks

The disks — available in differing capacities — fit into slots The disks — available in differing capacities — fit into slots in the
enclosure. Each disk has a unique ID that you use when binding it or
monitoring its operation. The ID is the enclosure address (always 0
for the DPE, settable on a DAE) and the disk slot number.

EMC Fibre Channel Storage Systems Configuration Planning Guide

Storage System Hardware

5

Figure 5-7 Disks and Disk IDs

Storage Processor (SP)

0
1
2
3

4
5
6
7
8
9

10
11
12
13

14
15
16
17

18

19

0

1 2

3

4 5

6 7

8

9

The SP provides the intelligence of the storage system. Using its own
operating system (called Core Software), the SP processes the data
written to or read from the disk modules, and monitors the modules
themselves. An SP consists of a printed-circuit board with memory
modules (DIMMs), status lights, and switches for setting FC-AL
addresses.

For high availability, a storage system can support a second SP. A
second SP provides a second route to a storage system, so both SPs
can connect to the same server or two different servers, as follows.

Hardware for Unshared Storage

5-9

Storage System Hardware

5

Server

Adapter

Adapter

Storage system

DAE(s)

DPE

SP A

Cables

FC loop 1
FC loop 2

Figure 5-8 Storage System with Two SPs Connected to the Same Server

Highly available cluster

SP B

5-10

Server 2Server 1

Adapter

Adapter

FC loop 1
FC loop 2

Figure 5-9 Storage System with Two SPs Connected to Different Servers

Adapter

Adapter

Storage system

SP A

Either SP can control any LUN in the storage system, but only one SP
at a time can control a LUN. If one SP cannot access a LUN it
controlled (because of a failure), you can transfer control of the LUN
to the other SP, manually or via software.

EMC Fibre Channel Storage Systems Configuration Planning Guide

DAE(s)

DPE

SP B

Storage-system caching provides significant performance
enhancement. Read caching is available with one or two SPs.
Mirrored write caching, particularly helpful with RAID 5 I/O,
requires two SPs (to mirror one another, for cache integrity) and a
Standby Power Supply (SPS) to enable the SPs to write their cached
data to disk if power fails.

Planning Your Hardware Components

This section helps you plan the hardware components — adapters,
switches or hubs, cables, storage systems, and site requirements —
for each server in your installation.

For shared storage, you must use a DPE rackmount system with two
SPs and high-availability options. We assume you have some idea of
how many servers, adapters, switches or hubs, storage systems, and
SPs you want. Skip to the component data sheets following.

For unshared storage, you can use one or two SPs and you can choose
among storage system configurations. This section assumes you have
examined the configurations shown starting on page 4-2 and have
some idea of how many servers, adapters, switches or hubs, storage
systems, and SPs you want. It ends with blank worksheets and
sample worksheets.

Storage System Hardware

5

Configuration Tradeoffs - Shared Storage

The hardware configuration required for shared storage is very
specific: two host-bus adapters in each attached server, two Fibre
Channel switches, and two SPs per storage system. Choices you can
make with shared storage systems include the number of storage
systems (up to 15 are allowed), and for each storage system the cache
configuration (maximum or minimum), and one or two standby
power supplies (SPS units).

The number of storage systems in the SAN depends on the servers’
processing demands. For each system, the larger cache improves
write performance for very large processing loads; the redundant SPS
lets write caching continue if one SPS fails.

Planning Your Hardware Components

5-11

Storage System Hardware

5

Configuration Tradeoffs - Unshared Storage

For each storage-system enclosure, you have two important areas of
choice: rackmount or deskside model, and high-availability options.

Generally, rackmount systems are more versatile; you can add
capacity in a cabinet without consuming more floor space. However,
rackmount systems require additional hardware, such as cabinets
and mounting rails, and someone must connect power cords and
cables within them. For large storage requirements, rackmount
systems may be more economical than deskside systems. Deskside
systems are more convenient; they ship with all internal cabling in
place and require only ac power and connection to the servers.

For high availability, there are many variations. The most important
high-availability features are a second SP/LCC pair, second power
supply, and standby power supply (SPS). The second SP/LCC and
SPS let you use write caching to enhance performance; the second SP
provides continuous access to storage-system disks if one SP or LCC
fails. Another high-availability option is a redundant SPS.

Yet another option, for a deskside system, is a second power
distribution unit (PDU), which lets you route ac power from an
independent source. Used this way, the second PDU protects against
failure in one of the two ac power sources. With a rackmount system,
you can acquire a cabinet with one or two ac inlet cords. The second
inlet cord, connected to a second ac power source, provides the same
advantage for all storage systems in the cabinet as the second PDU in
the deskside storage system.

5-12

For deskside systems, the optional high-availability hardware fits
into the deskside cabinet. Deskside high-availability options are as
follows.

EMC Fibre Channel Storage Systems Configuration Planning Guide

Table 5-1 High-Availability Options, Deskside Unshared Storage

Storage System Hardware

5

Deskside
System Type HA Level PDUs SPs LCCs

DPE Minimum 1 1 1 DPE

1 DAE

Maximum 2 2 4 (2 DPE

2 DAE)

iDAE Minimum 1 1 n/a (10-slot)

2 (30-slot)

Maximum 2 2 n/a (10-slot)

4 (30-slot)

DAE only Minimum 1 n/a 1 1 No minimum n/a

Maximum 2 n/a 2 2 No minimum n/a

Power
Supplies Disks SPS Units

1 DPE
1 DAE

4
(2 DPE
2 DAE)

1 3 (without write

2 (10-slot)
6 (30-slot)

5 (without write
cache)

10 (write cache
or RAID 3)

cache)
5 (write cache

or RAID 3)

5 (write cache
or RAID 3)

0 (without write
cache)

1 (write cache)

2

0 (without write
cache)

1 (write cache

2

For rackmount systems, the standby power supply or supplies (SPS
or BBU) must be placed in a tray directly beneath the storage system.
Typically, any hubs in the cabinet mount at the top or bottom of the
cabinet. Rackmount options are as follows.

Table 5-2 High-Availability Options, Rackmount Unshared Storage

Rackmount
System Type HA Level SPs LCCs

DPE Minimum 1 1 1 5 (without write

Maximum 2 2 (DPE)

18 (with 9
DAEs)

iDAE Minimum 1 n/a (10-slot)

4 (with two
DAEs)

Maximum 2 n/a 2 5 (write cache or

DAE only Minimum n/a 1 1 No minimum n/a

Maximum n/a 2 2 No minimum n/a

Power
Supplies Disks SPS Units

cache)

2 (DPE)
11 (with 9

DAEs)

1 3 (without write

10 (write cache or
RAID 3)

cache)
5 (write cache or

RAID 3)

RAID 3)

Planning Your Hardware Components

0 (without write
cache)

1 (write cache)

2

0 (without write
cache)

1 (write cache

2

5-13

Storage System Hardware

m

)

y

5

Hardware Data Sheets

The hardware data sheets shown in this section provide the plant
requirements, including dimensions (footprint), weight, power
requirements, and cooling needs, for DPE, iDAE, DAE, and 30-slot
SCSI disk systems. Sections on cabinets and cables follow the data
sheets.

DPE Data Sheet

Deskside model Rackmount model

Depth

74.7 cm
(30 in)

Width

52.1 cm
(20.6 in)

For shared storage, a rackmount DPE and one or more rackmount
DAEs are required. For unshared storage, you can use a rackmount or
deskside DPE and DAE(s). The DPE dimensions and requirements
are shown in the following figure.

DPE Dimensions and Requirements

Width

Depth
70 cm
(27.6 in)

Height
68 cm
(26.8 in)

44.5 cm
(17.5 in)

Height

28.6 c
(11.3 in

6.5 U

SPS mounting tra
height 4.44 cm

(1.75 in), 1 U;
depth 54.1 cm
(21.3 in)

5-14

Weight (without packaging) Deskside Rackmount

Maximum (max disks, SPs,

144 kg (316 lb) 52 kg (115 lb)

LCCs, PSs):

with 2 SPSs 165 kg (364 lb) 74 kg (163 lb)

EMC Fibre Channel Storage Systems Configuration Planning Guide

Storage System Hardware

Power requirements

Voltage rating: 100 V ac to 240 V ac –10%/+15%,

single-phase, 47 Hz to 63 Hz;
power supplies are auto-ranging

Current draw: At 100 v ac input – Deskside

DPE/DAE: 12.0 A; Rackmount
DPE: 8.0 A max; SPS: 1.0 A max per
unit during charge

Power consumption: Deskside DPE/DAE: 1200 VA;

Rackmount DPE: 800 VA max SPS:

1.0 A per unit during charge

Power cables (single or dual)

ac inlet connector: IEC 320-C14 power inlet
Deskside power cord: USA: 1.8 m (6.0 ft):

NEMA 6-15P plug

Outside USA Specific to country

Operating environment

Te mp er at ur e: 1 0oC to 40oC (50o F to 104o F)
Relative humidity: Noncondensing, 20% to 80%
Altitude: 40

o

C to 2,438 m (8,000 ft); 37oC to 3,050 m

(10,000 ft)

3

Heat dissipation (max): Deskside DPE/DAE: 3931x10

J/hr (2730

BTU/hr) max estimated;
Rackmount DPE: 2520x10

3

J/hr (2390

BTU/hr) max estimated

Air flow: Front to back

5

Service clearances
Front: 30.3 cm (1 ft)
Back: 60.6 cm (2 ft)

Hardware Data Sheets

5-15

Storage System Hardware

5

iDAE Data Sheet

You can use a rackmount or deskside DPE and DAE(s) for unshared
storage. The iDAE dimensions and requirements are shown in the
following figure.

Dimensions and Requirements, iDAE

Deskside 30-slot model Rackmount model

Depth

74.7 cm
(30 in)

Width

52.1 cm
(20.6 in)

Height
68 cm
(26.8 in)

Weight (without
packaging) Deskside 30 Deskside 10 Rackmount

Maximum (max

Deskside 10-slot model

Width
25 cm

Depth

74.7 cm
(30 in)

(9.8 in)

144 kg (316 lb) 60 kg (132 lb) 35.4 kg (78 lb)

Depth

63.3 cm
(24.9 in)

SPS mounting tray,
height 4.44 cm

(1.75 in), 1 U;
depth 69.9 cm
(27.5 in)

disks, SPs):

Width

44.5 cm
(17.5 in)

Height

15.4 cm
(6.1 in)

3.5 U

5-16

Power requirements

Voltage rating: 100 V ac to 240 V ac +/- 10%, single-phase,

47 Hz to 63 Hz; power supplies are
auto-ranging

Current draw: At 100 v ac input – 30-slot 12.0 A; 10-slot: 4.0

A; SPS: 1.0 A max per unit during charge

Power consumption: 30-slot: 1200;10-slot: 400 VA; SPS: 100 VA

per unit during charge

EMC Fibre Channel Storage Systems Configuration Planning Guide