Dell PowerVault MD1000 SAS Solution Manual
A Reference Guide for Optimizing the
Dell™ PowerVault™ MD1000 SAS Solution
Authored By:
SAS Solution Team
April, 2006 rev A01
HIS WHITE PAPER IS FOR INFORMATION PURPOSES ONLY, AND MAY CONTAIN TYPOGRAPHICAL ERRORS AND TECHNICAL
T
INACCURACIES. THE CONTENT IS PROVIDED AS IS WITHOUT EXPRESS OR IMPLIED WARRANTIES OF ANY KIND.
____________________
Information in this document is subject to change without notice.
© Copyright 2006 Dell Inc. All rights reserved.
Reproduction in any manner whatsoever without the written permission of Dell Inc. is strictly forbidden.
Dell, the Dell Logo, PowerVault, PowerEdge and OpenManage are trademarks of Dell Inc. Microsoft is a
registered trademark of Microsoft Corporation. Other trademarks and trade names may be used in this
document to refer to either the entities claiming the marks and names or their products. Dell disclaims
proprietary interest in the marks and names of others.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00
TABLE OF CONTENTS
1. INTRODUCTION ...................................................................................................................................................................4
Serial Attached SCSI (SAS)....................................................................................................................................................5
2. RECOMMENDED MAINTENANCE FOR YOUR DELL POWERVAULT MD1000 SAS SOLUTION ......................................... 6
3. DELL’S SAS PRODUCT OFFERING .....................................................................................................................................7
SAS Cabling............................................................................................................................................................................8
Physical Drive Support ..........................................................................................................................................................8
3rd Party Hardware support...................................................................................................................................................9
Server Support........................................................................................................................................................................ 9
4. POWERVAULT MD1000 STORAGE ENCLOSURE DETAILS................................................................................................9
Enclosure Modes ....................................................................................................................................................................9
Unified Topology.................................................................................................................................................................... 9
Split Topology.......................................................................................................................................................................10
Daisy-Chaining Multiple PowerVault MD1000 Storage Enclosures................................................................................10
PowerVault MD1000 – Common Features and Capabilities............................................................................................11
5. PERC 5/E CONTROLLER - DETAILED FEATURES ............................................................................................................15
Considerations when implementing a RAID Solution........................................................................................................15
Controller Features ................................................................................................................................................................................15
Capacity Requirements...........................................................................................................................................................................17
6. DELL OPENMANAGE SERVER ADMINISTRATOR.............................................................................................................19
Managing the PERC 5/E Controller and the PowerVault MD1000 Storage Enclosure..................................................19
Using the Create Virtual Disk Wizards ...............................................................................................................................19
Reconfiguring Virtual Disks -- RAID Migration and Capacity Expansion .......................................................................20
Moving Physical Disks and Virtual Disk Configurations – Disk Roaming and Disk Migration .....................................21
Importing Migrated Virtual Disks .......................................................................................................................................22
Upgrading from Dell OpenManage Array Manager.........................................................................................................24
7. STORAGE APPLICATIONS AND COMPONENTS..................................................................................................................25
Identify customer usage model and needs...........................................................................................................................25
Picking a solution based on the application profile............................................................................................................ 26
Application specific guidelines ............................................................................................................................................27
E-Mail Servers ........................................................................................................................................................................................27
Web Servers.............................................................................................................................................................................................28
Database or Online Transaction Processing Servers...........................................................................................................................29
File Servers..............................................................................................................................................................................................30
Streaming Media Servers........................................................................................................................................................................32
Hot Spares.............................................................................................................................................................................33
8. SUMMARY AND CONCLUSIONS ........................................................................................................................................ 33
9. APPENDIX – A: REFERENCES............................................................................................................................................35
10. APPENDIX – B: GLOSSARY...........................................................................................................................................35
11. APPENDIX – D: REVISION HISTORY.............................................................................................................................35
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1. Introduction
A complete enterprise storage solution involves various software and hardware components. A
given storage project can be addressed using several approaches. Therefore, it is essential to
identify optimum storage solutions for different applications.
Selecting the right storage components not only impacts the effectiveness of a given application
but may also improve the performance of the entire IT infrastructure which relies on that storage.
See table 1 for examples of key storage components.
Table 1: Examples of the components in a typical storage solution
Storage Solution Components Examples
Physical Storage Device Technology Storage Expansion Enclosure (e.g., PowerVault
MD1000)
Interconnect Technology 3 Gbps Serial Attached SCSI (SAS)
Host System Interface Technology Non-RAID (HBA) or RAID controllers (e.g. PowerEdge
Expandable Raid Controller)
Management Capabilities Dell OpenManage Server Administrator
As with many IT solutions, storage deployments can be assessed using numerous criteria, each
with varying levels of importance. In general, the effectiveness of a given storage solution should
be measured using the following attributes:
• Reliability – The solution remains functional and ensures that data is unaltered
• Availability – Data remains accessible by the application.
• Serviceability – The hardware has easy access to assemblies/components, allowing easy
maintenance and replacement.
• Redundancy – The hardware provides redundancy for both the data storage, as well as
for the hardware management capabilities.
• Performance
o Bandwidth Utilization – Data throughput / available Bandwidth
o IOPS – I/Os per second
• Data Protection – Data is protected against catastrophic system failure or components
failure.
• Scalability – Storage capacity can be expanded as the application necessitates.
• Cost – Measured in total lifetime cost, acquisition cost, or $ per Gigabyte.
An optimal storage solution addresses all key attributes to a greater or lesser extent depending on
their relative importance. This paper presents a study of the technological, functional and
behavioral differences of the storage solution components and measures them against the
attributes listed above. Understanding each component with respect to these attributes will help in
making informed decisions about the optimal solution for a given storage application.
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The paper presumes that the reader has a basic understanding of different RAID levels and
interconnect technologies – such as Serial Attached SCSI (SAS) and PCI Express. In this paper,
we will focus on Serial Attached SCSI storage technology, specifically for Dell’s PowerVault
MD1000 storage expansion enclosure and Dell’s PERC 5/E RAID controller. Other storage
technologies such as SCSI or Fibre Channel, as well as topologies such as Network Attached
Storage (NAS) or Storage Area Network (SAN) are outside the scope of this document. All storage
applications will be treated independent of any specific host system or server.
Serial Attached SCSI (SAS)
The SCSI (Small Computing System Interface) protocol originated more than 20 years ago and is
used in the majority of server storage needs (e.g. storage that is internal to a server or physically
connected to a server in an external disk expansion enclosure). The market prevalence of SCSI
has created economies of scale making it one of the most affordable storage interconnect
technologies available today. Many businesses rely on SCSI physical disks to help deliver
extremely cost-effective and reliable storage. In fact, SCSI physical disks have advanced over the
years offering increased performance and more sophisticated features with each iteration.
However, given the inherent limitations of its parallel architecture, the current version of SCSI
physical disks, U320 or Ultra320, will be the last version of the traditional SCSI technology.
Serial Attached SCSI (SAS) is a major iteration of SCSI technology and introduces a host of
benefits when compared to older SCSI technology including,
Dramatic improvement in bandwidth performance
• The first generation of SAS will support 3.0 Gbps (or 300 MB/sec) per “lane”
• Ultra320 SCSI is the shared-bus architecture. SAS introduces a point to point topology
enabling systems with many physical disks to scale bandwidth far beyond the bandwidth
capacity of Ultra320 SCSI.
Figure 1: Parallel U320 SCSI bus versus point to point Serial Attached SCSI connection
• SAS introduces the concept of port aggregation to storage interconnects. External storage
devices can connect via a x4 (“by four”)wide-lane. Cabling aggregates four SAS lanes, each
operating at 3.0 Gbps, for a full external connection bandwidth of up to 12.0 Gbps on a single
connector.
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Up to320 MBps
Up to 3.0 Gbps per link
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00
One parallel SCSI cable
One
x4
SAS cable
Figure 2: Bandwidth improvement with SAS port aggregation
Up to 320MB/s
Up to 12.0 Gbps performance
Improved capacity scalability
• SAS allows for port expansion, enabling the ability to “daisy-chain” storage enclosures for
dramatic improvements in capacity scalability. With Ultra320 SCSI, systems were limited to a
maximum of 16 devices on a single SCSI channel. This typically translated to maximum of 14
physical disks connected to a single SCSI channel on a RAID controller. With SAS expansion,
a single SAS port can be expanded out to multiple SAS devices (similar to how Ethernet hubs
can expand a single Ethernet connection into multiple devices).
Other important changes to keep in mind about SAS:
• SAS continues to use the SCSI command sets for driver & software compatibility.
• SAS is not backwards compatible with Parallel SCSI.
2. Recommended Maintenance for your Dell PowerVault MD1000 SAS Solution
Dell strives to provide the best possible customer experience for all of our enterprise server and
storage products. Proper maintenance of your solution is essential to help ensure that the
equipment remains in optimal working condition. Dell recommends the following suggested
maintenance activities.
Keep firmware/drivers/utilities up to date
In general, Dell posts planned maintenance updates for firmware twice a year. To stay current
with the latest updates, customers can subscribe to Dell notification tools. Click the following link
to sign up for technical updates.
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http://support.dell.com/support/topics/global.aspx/support/notifications/en/index?c=us&l=en&s
=gen
Enable Background Read Patrol
Background Read Patrol, a function of the RAID controller, is an automatically scheduled
background task that scans and helps resolve possible physical disk errors that may lead to
physical disk failure and result in data integrity issues. Dell recommends implementing Background
Read Patrol in all configurations.
See section 5 for details.
Schedule and run periodic consistency checks / Background Initialization (BGI)
Consistency checks / BGI are performed by many RAID controllers to verify that all stripes in a
redundant virtual disk are consistent and to automatically correct stripes where inconsistencies are
found. BGI is a consistency check that automatically runs on all redundant arrays. Depending on
workload, Dell recommends that consistency checks should be run manually on the virtual disks at
least once every month to help ensure data integrity. Consistency checks and Background Read
Patrol are complementary and both should be used.
See section 5 for details.
Enable Hot Spares
Hot spare functionality provides extra security, availability and redundancy by automatically
replacing a failed disk in a RAID group and allowing the rebuild of the degraded array to begin
immediately. Dell PERC controllers support Hot Spare functionality and it is recommended
whenever possible.
See section 5 for details.
Document your configuration and keep the documentation current
Documenting your configuration facilitates faster and easier recovery should a failure occur. Make
sure to include RAID levels, physical disks included in your virtual disks, firmware and driver
versions and usage of hot spares in your documentation.
Perform periodic physical inspection of your connections and cabling
Damaged cables and loose connections may cause functional issues with your storage solution.
Dell recommends a physical equipment audit two times a year or anytime after re-cabling or redeploying your storage hardware.
3. Dell’s SAS Product Offering
The PowerVault MD1000 is a feature-optimized storage expansion enclosure which utilizes the
latest industry standard storage interconnect technology, Serial Attached SCSI (SAS). This 3U
enclosure supports between 2 and 15 physical SAS drives. Along with Dell’s host-based RAID
controller, PERC 5/E, the PowerVault MD1000 storage enclosure introduces new levels of
performance, capacity, and scalability. Major features of the PowerVault MD1000 and PERC 5/E
solution include:
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Performance
• Support for 3.0 Gbps SAS physical disks (both 10,000 and 15,000 RPM)
• External cable supports a SAS x4 wide-lane to achieve a total interface bandwidth of up to
12.0 Gbps connection to the host controller
• Host interconnect with the PERC 5/E host-based controller
• Support for RAID level 0
Availability
• Support for RAID levels 1, 5, 10 and 50
• Redundant, hot pluggable power supplies with integrated cooling fan modules
• Redundant enclosure management modules (EMMs)
• Hot pluggable physical disks
Scalability/Expandability
• Support for daisy-chaining up to three PowerVault MD1000 expansion enclosures per PERC
5/E connection
• Supports between 2 and 15 physical SAS drives
• Supports 36GB, 73GB, 146GB, and 300 GB 3.5-inch SAS physical disks
Ease-of-Use
• Common management software with PowerEdge™ servers through Dell OpenManage Server
Administrator
PERC 5/E is the RAID controller used to connect the PowerVault MD1000 storage enclosure to
one or two PowerEdge servers. It supports 3 Gbps Serial Attached SCSI (SAS) as the storage
interconnect technology and PCI Express (PCI-E) as the host-based interconnect technology. The
“E” in PERC 5/E stands for “External” because the PERC 5/E controller supports only physical
disks that attach to a server externally.
The PERC 5/E controller offers:
• Intel IOP333 I/O processor based on Intel XScale Microarchitecture
• 256MB of customized DDR2 400MHz, Error-Correcting Code (ECC) cache memory
• 3 Gbps maximum speed for each SAS lane
• Two external x4 (“by four”) SAS ports, each aggregating 4 SAS lanes for a total bandwidth per
port of 12.0 Gbps
• x8 PCI E host interface for a total bandwidth of 32.0 Gbps
• Up to 72 hours of intelligent, transportable, battery-backed, cache memory
For detailed information on the PERC 5/E controller, see section 6.
SAS Cabling
The PowerVault MD1000 storage enclosure and the PERC 5/E controller both support industry
standard 3.0 Gbps SAS cables in 1m, 2m, and 4m cable lengths. Each cable supports x4 SAS
connectors to deliver up to 12.0 Gbps of total bandwidth from the host to the enclosure. Only Dellqualified cables are supported for connecting the PowerVault MD1000 storage enclosure to the
PERC 5/E controller.
Physical Drive Support
The PowerVault MD1000 storage expansion enclosure supports the latest SAS physical disks,
currently specified as 3.0 Gbps SAS. SAS solutions from Dell include both 10,000 RPM and
15,000 RPM spindle speeds and a variety of capacities to allow customers the maximum flexibility.
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For the latest information on support for specific physical disks, see the Dell Storage web site at:
http://www.us.dell.com/storage/
3rd Party Hardware support
To help provide the best possible customer experience, Dell supports only hardware purchased
direct from Dell for the PowerVault MD1000 and PERC 5/E controller. Dell-developed server and
storage solutions include many thousands of person-hours of engineering testing and validation to
help ensure the highest product quality. For example, physical disks purchased direct from Dell
may include features not generally available to the rest of the industry. As such, Dell supports only
Dell tested and qualified hardware. Hardware purchased direct from Dell carries the full Dell
system limited warranty
1
and helps ensure full compatibility. Materials purchased from 3rd party
vendors for use in Dell systems are not covered under Dell’s limited warranty and may not deliver
an acceptable customer experience.
Server Support
The PowerVault MD1000 storage enclosure and PERC 5/E solution are supported on the
PowerEdge 1850, 2850, 6800, and 6850 servers.
4. PowerVault MD1000 Storage Enclosure Details
Enclosure Modes
The enclosure can be set to either unified or split mode through the use of a two-position switch
located on the front panel of the enclosure. The enclosure can be configured into the selected
mode only at power up. Any changes to the mode switch made while the enclosure is powered on
will not take effect until the enclosure is powered off and back on again.
Note: Any time you power on the PowerVault MD1000 storage enclosure, ensure the mode switch
is set in the desired position. If the position of the switch changes inadvertently, data loss could
occur as the controller may recognize an inaccurate number of attached physical disks versus the
previous mode. In order to cycle power on your MD1000, all attached servers, must be turned off.
Unified Topology
In unified mode, a single server has access to all fifteen physical disks in the PowerVault MD1000
storage enclosure through a single SAS cable. The unified mode can also provide a single server
access to a maximum of forty five physical disks by daisy-chaining up to three enclosures from a
single host port. The main advantage of unified mode is that it provides a high degree of physical
disk scalability.
1
For a copy of our guarantees or limited warranties, please write Dell USA L.P., Attn: Warranties, One Dell Way, Round
Rock, TX 78682. For more information, visit www.dell.com/warranty.
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Split Topology
In split mode, the enclosure is divided into two logical enclosures; with each host connection
accessing its own set of physical disks. The primary Enclosure Management Module (EMM)
(located on the left side of the enclosure when viewed from the rear), accesses physical disk slots
7 through 14. The secondary EMM accesses physical disk slots 0 through 6. To connect a server
to an enclosure in split mode, the In port of each EMM should be attached to a connector of a
PERC 5/E controller. The Out port of an EMM in split mode is disabled, since enclosure daisy-
chaining is not supported in this mode.
Split mode is useful in deployments where a single PowerVault MD1000 storage enclosure help
provide limited amounts of storage each for two different servers.
Note: In split mode, each host server can see its own physical disks (e.g. drive., physical disk 0 – 6
or 7 – 14) but not the other server’s physical disks.
Note: Split mode does not support daisy-chaining.
Note: A system with a single EMM set in split mode will function properly, but the server will only
be able to see the physical disks that are connected to the EMM.
Dual Hosts
Figure 3: Split mode configuration
Daisy-Chaining Multiple PowerVault MD1000 Storage Enclosures
In unified mode, up to three enclosures may be daisy-chained together from a single PERC 5/E
controller port. A maximum of six PowerVault MD1000 storage enclosures (3 enclosures per port)
may be connected to a single PERC 5/E controller. (Note: Although this is a supported
configuration, one should consider total solution availability before attaching this quantity of storage
to a single-controller solution.). When connecting multiple enclosures, the first enclosure is
connected to the PERC 5/E controller via the In port of the primary EMM. The second enclosure is
connected from the Out port of the primary EMM on the first enclosure to the In port of the primary
EMM on the second enclosure. The connection is made with a standard SAS cable. The third
enclosure is connected in the same manner as the second enclosure.
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A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00
Figure 4: Max configuration on a single PERC 5/E controller port
Figure 5: Max configuration on a single PERC 5/E controller (both ports connected)
PowerVault MD1000 – Common Features and Capabilities
Regardless of the topology, the PowerVault MD1000 storage enclosure provides a set of common
features and capabilities.
World Wide Name (WWN) Assignment
The SAS standard requires that all devices on a SAS domain have a unique address, called a
World Wide Name or WWN. The PowerVault MD1000 storage enclosure complies with the SAS
standard. For more information on WWN assignment, please refer to the SAS Specification
referenced in Appendix A.
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