Avago Technologies SATA 150-4 User Manual

USER’S

GUIDE

MegaRAID

Configuration Software

March 2006

Version 2.0

DB15-000269-01

This document contains proprietary information of LSI Logic Corporation. The information contained herein is not to be used by or disclosed to third parties without the express written permission of an ofﬁcer of LSI Logic Corporation.

LSI Logic products are not intended for use in life-support appliances, devices, or systems. Use of any LSI Logic product in such applications without written consent of the appropriate LSI Logic ofﬁcer is prohibited.

Purchase of I Associated Companies, conveys a license under the Philips I use these components in an I

C standard Speciﬁcation as deﬁned by Philips.

the I

C components of LSI Logic Corporation, or one of its sublicensed

C system, provided that the system conforms to

C Patent Rights to

Document DB15-000269-01, Second Edition (March 2006) This document describes LSI Logic Corporation’s MegaRAID software tools and utilities. This document will remain the ofﬁcial reference source for all revisions/releases of these products until rescinded by an update.

LSI Logic Corporation reserves the right to make changes to any products herein at any time without notice. LSI Logic does not assume any responsibility or liability arising out of the application or use of any product described herein, except as expressly agreed to in writing by LSI Logic; nor does the purchase or use of a product from LSI Logic convey a license under any patent rights, copyrights, trademark rights, or any other of the intellectual property rights of LSI Logic or third parties.

LSI Logic, the LSI Logic logo design, FlexRAID, MegaRAID, MegaRAID Conﬁguration Utility, MegaRAID Manager, and Power Console Plus are trademarks or registered trademarks of LSI Logic Corporation. Intel and Pentium are registered trademarks of Intel Corporation. Linux is a registered trademark of Linus Torvalds. Microsoft, MS-DOS, Windows, and Windows NT are registered trademarks of Microsoft Corporation. NetWare,Novell, and SUSE are trademarks or registered trademarks of Novell, Inc. PCI-X is a registered trademark of PCI SIG. Red Hat is a registered trademark of Red Hat Software, Inc. All other brand and product names may be trademarks of their respective companies.

To receive product literature, visit us at http://www.lsilogic.com. For a current list of our distributors, sales ofﬁces, and design resource

centers, view our web page located at

http://www.lsilogic.com/contacts/index.html

Preface

Audience

This book is the primary reference and user’s guide for the MegaRAID software tools and utilities. These include the MegaRAID BIOS Conﬁguration Utility (CU), WebBIOS CU, MegaRAID Manager™, and Power Console Plus™, which enable conﬁguration and management of RAID systems using the MegaRAID controllers.

This document assumes that you have familiarity with storage systems, and are knowledgeable about PCI, SCSI, and Serial ATA interfaces. It also assumes that you are familiar with computer systems and know how to use the keyboard, mouse, clipboard functions, toolbars, and drop down menus.

The people who beneﬁt from this book are:

• Users who want to conﬁgure, monitor, or manage RAID systems that

use MegaRAID controllers

• Engineers and managers who are evaluating MegaRAID controllers

for use in a system

• Engineers who are designing MegaRAID controllers into a system

Organization

This document has the following chapters and appendix:

• Chapter 1, Overview, introduces the MegaRAID software tools and

utilities, and provides operating system information.

• Chapter 2, Introduction to RAID, describes the components,

functions and beneﬁts of RAID, along with RAID levels, conﬁguration strategies, and conﬁguration planning.

MegaRAID Conﬁguration Software User’s Guide iii

• Chapter 3, BIOS Conﬁguration Utility and MegaRAID Manager,

describes the MegaRAID BIOS CU.

• Chapter 4, WebBIOS Conﬁguration Utility, describes the

WebBIOS CU.

• Chapter 5, Start the Power Console Plus Utility, describes the

Power Console Plus tool.

• Chapter 6, Virtual Sizing and Online Capacity Expansion,

describes the FlexRAID Virtual Sizing feature and capacity expansion under Linux.

• Appendix A, MegaRAID Service Monitor, describes the messages

used by the MegaRAID Service Monitor.

MegaRAID System Installation Sequences and Document Organization

The following table outlines the installation, conﬁguration, and management sequences for a MegaRAID Serial ATA system. Each sequence consists of a series of steps and operations that the reference manual explains. LSI Logic recommends performing the sequences in the order listed when you install and conﬁgure your Serial ATA system.

Sequence Task Reference Manual

1 Understand RAID system theory and operation. MegaRAID Conﬁguration

2 Install the MegaRAID Serial ATA (SATA) or SCSI storage

3 Conﬁgure the physical arrays and logical devices using

4 Install the MegaRAID device drivers. MegaRAID Device Driver

5 Manage, monitor, and reconﬁgure the RAID array using

iv Preface

adapter and the related hardware.

either the MegaRAID Conﬁguration Utility WebBIOS CU.

either the MegaRAID Manager tool or the Power Console Plus tool. Each tool runs under an operating system and can manage the RAID array while the system is operating.

™

(CU) or the

Software User’s Guide MegaRAID 320 Storage

Adapters User’s Guide, MegaRAID SATA150 PCI to Serial ATA Storage Adapters User’sGuide, and MegaRAID SATA 300 Storage Adapters User’s Guide

MegaRAID Conﬁguration Software User’s Guide

Installation User’s Guide MegaRAID Conﬁguration

Software User’s Guide

Related Publications

MegaRAID SA TA150 PCI to Serial ATA Storage Adapters User’s Guide

Document Number: DB15-000272-04

This document explains how to install your MegaRAID SATA 150 storage adapter in the host system. It provides the electrical and physical speciﬁcations, jumper deﬁnitions, and connector locations for the storage adapter.

MegaRAID SATA 300 Storage Adapters User’s Guide

Document Number: DB15-000311-02

This document explains how to install your MegaRAID SATA 300 storage adapter in the host system. It provides the electrical and physical speciﬁcations, jumper deﬁnitions, and connector locations for the storage adapter.

MegaRAID 320 Storage Adapters User’s Guide

Document Number: DB15-000260-06

This document explains how to install your MegaRAID 320 storage adapter in the host system. It provides the electrical and physical speciﬁcations, jumper deﬁnitions, and connector locations for the storage adapter.

MegaRAID Device Driver Installation User’s Guide

Document Number: DB11-000018-02

This document explains how to install the MegaRAID device driver for your operating system. The information in this document is independent of the back-end bus and applies to both MegaRAID SCSI storage adapters and Serial ATA storage adapters.

Preface v

Conventions

Throughout the manual, the following conventions are used to describe user interaction with the product.

Notation Meaning and Use Examples

→ Used to indicate a series of

all caps, plus sign

courier typeface

bold typeface fd1sp In a command line, keywords are shown in bold, nonitalic

italics module In command lines and names, italics indicate user

Initial Capital letters

brackets [version] You may, but need not, select one item enclosed within

selections in a GUI. Key presses are in all caps,

with a plus sign (+) between key presses in a sequence

.nwk ﬁle Names of commands, directories, ﬁle names, and

Undo Edit Apply

Start → Programs

ENTER, ALT+CTRL+DEL, TAB

on-screen text are shown in courier typeface.

typeface. Enter them exactly as shown.

variables. Italicized text must be replaced with appropriate user-speciﬁed items. Enter items of the type called for, using lowercase.

Names of menu commands, options, check buttons, text buttons, options buttons, text boxes, list boxes, etc., are shown in text with Initial Capital lettering to avoid misreading. These elements may appear on your screen in all lowercase.

brackets. Do not enter the brackets.

vi Preface

Revision History

Document Number Version/Date Description

DB15-000269-01 Version 2.0

February 2006

DB15-000269-00 Version 1.0

February 2003

Technical Support

LSI provides technical support only for LSI products purchased directly from LSI or from an LSI-authorized reseller.

If you purchased the MegaRAID controller from LSI or from a certiﬁed LSI reseller, call LSI technical support at support@lsil.com, 1-800-633-4545 #3, or 1-678-728-1250. Please be prepared to specify the 10-digit number preceded by the letter “E”.

In Europe, you can contact LSI Technical Support at eurosupport@lsil.com or +44.1344.413.441 (English).

If the MegaRAID controller was installed as part of a system manufactured by a company other than LSI, or if you purchased an LSI product from an unauthorized reseller, call the technical support department of the computer manufacturer or the unauthorized reseller. LSI does not provide direct technical support in these cases.

Added the introduction to RAID chapter. Revised supported operating systems, spanning, and menu options, and added port multiplier information in the BIOS Conﬁguration Utility. Revised information about virtual sizing. Revised the WebBIOS Adapter Properties Menu and the Conﬁguration Wizard procedure.

Initial release of document.

To download drivers or documentation, go to the LSI web site at:

http://www.lsilogic.com/downloads/selectDownload.do.

Preface vii

viii Preface

Chapter 1 Overview

1.1 MegaRAID Tool Description 1-1

1.1.1 MegaRAID BIOS Conﬁguration Utility (Ctrl+M) 1-2

1.1.2 MegaRAID Manager Conﬁguration Utility 1-2

1.1.3 WebBIOS Conﬁguration Utility (CTRL+H) 1-2

1.1.4 Power Console Plus Conﬁguration Utility 1-2

1.2 Operating System Support 1-3

Chapter 2 Introduction to RAID

2.1 RAID Description 2-1

2.2 RAID Beneﬁts 2-2

2.3 RAID Functions 2-2

2.4 RAID Components and Features 2-3

2.4.1 Physical Array 2-3

2.4.2 Logical Drive 2-3

2.4.3 RAID Array 2-3

2.4.4 Fault Tolerance 2-3

2.4.5 Consistency Check 2-4

2.4.6 Background Initialization 2-4

2.4.7 Patrol Read 2-5

2.4.8 Disk Striping 2-6

2.4.9 Disk Mirroring 2-7

2.4.10 Parity 2-7

2.4.11 Disk Spanning 2-8

2.4.12 Hot Spares 2-9

2.4.13 Disk Rebuilds 2-11

2.4.14 SCSI Physical Drive States 2-12

2.4.15 Logical Drive States 2-13

2.4.16 Enclosure Management 2-13

MegaRAID Conﬁguration Software User’s Guide ix

2.5 RAID Levels 2-13

2.5.1 Summary of RAID Levels 2-13

2.5.2 Selecting a RAID Level 2-14

2.6 RAID Conﬁguration Strategies 2-19

2.6.1 Maximizing Fault Tolerance 2-19

2.6.2 Maximizing Performance 2-21

2.6.3 Maximizing Storage Capacity 2-22

2.7 RAID Availability 2-23

2.7.1 Spare Drives 2-23

2.7.2 Rebuilding 2-23

2.8 RAID Conﬁguration Planning 2-24

2.8.1 Number of Physical Disk Drives 2-24

2.8.2 Array Purpose 2-25

Chapter 3 BIOS Conﬁguration Utility and MegaRAID Manager

3.1 Quick Conﬁguration Steps for the BIOS Conﬁguration Utility 3-2

3.2 Quick Conﬁguration Steps for MegaRAID Manager 3-3

3.3 Conﬁguration Utility Menu 3-4

3.3.1 Conﬁgure Menu 3-5

3.3.2 Initialize Option 3-6

3.3.3 Objects Menu 3-6

3.3.4 Clear Option 3-14

3.3.5 Rebuild Option 3-14

3.3.6 Check Consistency Option 3-15

3.3.7 Reconstruct Option 3-15

3.3.8 Select Adapter Menu 3-15

3.4 Detailed Conﬁguration Instructions 3-16

3.4.1 Starting the MegaRAID Conﬁguration Utility 3-16

3.4.2 Resolving a Conﬁguration Mismatch 3-16

3.4.3 Starting MegaRAID Manager 3-17

3.4.4 Conﬁguring Arrays and Logical Drives 3-18

3.4.5 Selecting a Conﬁguration Method 3-18

3.4.6 Designating Drives as Hot Spares 3-18

3.4.7 Creating Physical Arrays and Logical Drives 3-19

3.4.8 Initializing Logical Drives 3-26

x Contents

3.5 Deleting Logical Drives 3-27

3.6 Performing Drive Roaming 3-27

3.7 Performing Drive Migration 3-29

3.8 Rebuilding Failed Disks 3-30

3.8.1 Rebuild Types 3-30

3.8.2 Manual Rebuild – Rebuilding an Individual Drive 3-31

3.8.3 Manual Rebuild – Rebuilding in Batch Mode 3-31

3.9 FlexRAID Virtual Sizing 3-32

3.10 Checking Data Consistency 3-32

3.11 Reconstructing Logical Drives 3-33

3.12 Replacing a Failed Controller Containing Data in the TBBU 3-34

3.13 Using a Preloaded System Drive 3-35

3.14 Exiting MegaRAID Conﬁguration Utility 3-36

Chapter 4 WebBIOS Conﬁguration Utility

4.1 General Description 4-1

4.2 Quick Conﬁguration Steps 4-2

4.3 Starting the WebBIOS Conﬁguration Utility on the Host Computer 4-2

4.4 Screen and Option Descriptions 4-4

4.4.1 WebBIOS Toolbar Options 4-4

4.4.2 Main Screen 4-5

4.4.3 Adapter Properties Screen 4-6

4.4.4 Scan Devices Option 4-9

4.4.5 SCSI Channel Properties 4-9

4.4.6 Logical Drive Screen 4-9

4.4.7 Physical Drive Screen 4-12

4.4.8 Conﬁguration Mismatch Screen 4-13

4.4.9 Conﬁguration Wizard Option 4-14

4.4.10 Adapter Selection Option 4-14

4.4.11 Physical View/Logical View Option 4-14

4.4.12 Exit 4-14

4.5 Conﬁguring RAID Arrays and Logical Drives 4-14

Contents xi

Chapter 5 Start the Power Console Plus Utility

5.1 Quick Conﬁguration Steps 5-1

5.2 Power Console Plus Overview 5-2

5.2.1 Power Console Plus Components 5-2

5.2.2 Features 5-3

5.2.3 Client System Requirements 5-4

5.2.4 MegaService Monitor 5-4

5.3 Installing the Power Console Plus Utility 5-5

5.3.1 Windows Installations 5-5

5.3.2 Deregistering and Reregistering under

the Power Console Plus Utility 5-11

5.4 Power Console Plus Interface Description 5-11

5.4.1 Power Console Plus Main Window Description 5-12

5.4.2 Power Console Plus Menus 5-14

5.4.3 Physical Drive Menu 5-16

5.4.4 Logical Drive Menu 5-17

5.4.5 Progress Menu 5-18

5.5 Conﬁguring Arrays and Logical Drives 5-19

5.5.1 Starting the Power Console Plus Utility 5-19

5.5.2 Choosing an Adapter 5-20

5.5.3 Running the Conﬁguration Wizard 5-20

5.5.4 Deﬁning Logical Drives 5-22

5.5.5 Saving the Conﬁguration 5-24

5.5.6 Initializing Logical Drives 5-25

5.5.7 Checking Rebuild Rate 5-25

5.5.8 Exiting the Power Console Plus Utility 5-25

5.6 Reclaiming Hot Spare Disks 5-25

5.7 Reconﬁguring Existing Arrays 5-26

5.7.1 Adding a Physical Drive to an Existing Array 5-26

5.7.2 Removing a Physical Drive from an Array 5-26

5.8 Add Capacity Steps 5-27

Chapter 6 Virtual Sizing and Online Capacity Expansion

6.1 FlexRAID Virtual Sizing 6-1

6.2 Capacity Expansion under the Linux Operating System 6-2

xii Contents

Appendix A MegaRAID Service Monitor

A.1 Power Console Plus Internal Messages A-1 A.2 MegaRAID Service Monitor Event Types A-3 A.3 Event Message IDs A-7

Index

Customer Feedback

Contents xiii

xiv Contents

Figures

2.1 Disk Striping (RAID 0) Example 2-6

2.2 Disk Mirroring (RAID 1) Example 2-7

2.3 Distributed Parity (RAID 5) Example 2-8

2.4 Disk Spanning (RAID 10) Example 2-9

2.5 RAID 10 Logical Drive 2-17

2.6 RAID 50 Logical Drive 2-19

3.1 MegaRAID Conﬁguration Utility Menu Tree 3-4

3.2 Port Multiplier Option 3-9

3.3 Port and Drive Information 3-9

4.1 WebBIOS Adapter Selection Screen 4-3

4.2 WebBIOS Main Screen 4-5

4.3 WebBIOS Adapter Properties Screen 4-6

4.4 WebBIOS Logical Drive Screen 4-10

4.5 WebBIOS Physical Drive Screen 4-12

4.6 WebBIOS Conﬁguration Mismatch Screen 4-13

4.7 WebBIOS Conﬁguration Wizard Screen 4-15

4.8 WebBIOS Logical Drive Deﬁnition Screen 4-16

xvi

Tables

1.1 MegaRAID Tool Operating System Support 1-3

2.1 Types of Parity 2-8

2.2 Disk Spanning for RAID 10 and RAID 50 2-9

2.3 SCSI Physical Drive States 2-12

2.4 Logical Drive States 2-13

2.5 RAID 0 Overview 2-15

2.6 RAID 1 Overview 2-15

2.7 RAID 5 Overview 2-16

2.8 RAID 10 Overview 2-17

2.9 RAID 50 Overview 2-18

2.10 RAID Levels and Fault Tolerance 2-20

2.11 RAID Levels and Performance 2-21

2.12 RAID Levels and Capacity 2-22

2.13 Physical Drives Required for Each RAID Level 2-24

2.14 Factors to Consider for Array Conﬁguration 2-25

3.1 Conﬁguration Utility Conﬁgure Menu 3-5

3.2 Conﬁguration Utility Objects Menu 3-6

3.3 Conﬁguration Utility Adapter Submenu 3-7

3.4 Conﬁguration Utility Logical Drive Submenu 3-10

3.5 Conﬁguration Utility View/Update Parameters Submenu 3-11

3.6 Conﬁguration Utility Physical Drive Submenu 3-13

3.7 Conﬁguration Utility Channel Submenu 3-13

3.8 Conﬁguration Utility Battery Backup Submenu 3-14

3.9 Conﬁguration Hot Keys 3-16

3.10 Logical Drive Parameters and Descriptions 3-21

3.11 Spanning Mode Options 3-25

3.12 Rebuild Types 3-30

4.1 WebBIOS Toolbar Icon Descriptions 4-4

4.2 WebBIOS Adapter Properties Menu Options 4-7

5.1 Power Console Plus Screen Elements 5-12

5.2 Power Console Plus Toolbar Icons 5-13

5.3 Power Console Plus Conﬁguration Menu 5-14

5.4 Power Console Plus Adapter Properties Menu 5-15

5.5 Power Console Plus Physical Drive Menu 5-16

5.6 Power Console Plus Change Status Submenu 5-16

5.7 Power Console Plus Logical Drive Menu 5-17

xvii

5.8 Power Console Plus Change Conﬁguration Submenu 5-17

5.9 Power Console Plus Read Policy Menu 5-18

5.10 Power Console Plus Write Policy Menu 5-18

5.11 Drive State Description 5-19

5.12 Custom Conﬁguration Wizard Options 5-21

A.1 Log Messages A-2 A.2 General Events Types and Log Messages A-3 A.3 Logical Drive Status Messages A-4 A.4 Physical Drive Status and Error Messages A-4 A.5 Messages for SAF-TE Compliant Boxes A-5 A.6 Battery Status Messages A-6 A.7 General Event Message IDs A-7 A.8 Test-Related Event Message IDs A-7

xviii

Chapter 1 Overview

This book describes the following software tools and utilities that enable conﬁguration and management of RAID systems using the MegaRAID controllers:

• MegaRAID BIOS Conﬁguration Utility (CU)

• WebBIOS CU

• MegaRAID Manager

• Power Console Plus

This chapter provides an overview of the MegaRAID software tools and explains the intended use of each tool. It consists of the following sections:

• Section 1.1, “MegaRAID Tool Description”

• Section 1.2, “Operating System Support”

1.1 MegaRAID Tool Description

MegaRAID products provide a powerful set of software products for conﬁguring and managing Redundant Array of Independent Disks (RAID) systems. The following subsections describe each software product. Subsequent chapters provide detailed information concerning each product.

You can use any of the listed utilities to conﬁgure your RAID system. Or, you can conﬁgure your RAID system with one utility and update it later with a different utility. All MegaRAID tools provide a full set of RAID array conﬁguration and monitoring features.

MegaRAID Conﬁguration Software User’s Guide 1-1

1.1.1 MegaRAID BIOS Conﬁguration Utility (Ctrl+M)

The MegaRAID BIOS Conﬁguration Utility (CU) provides full-featured, character-based conﬁguration and management of RAID arrays. The MegaRAID CU resides in the BIOS and is independent of the operating system. For information about the BIOS CU, refer to Chapter 3, “BIOS

Conﬁguration Utility and MegaRAID Manager.”

1.1.2 MegaRAID Manager Conﬁguration Utility

The MegaRAID Manager utility provides full-featured conﬁguration and management of RAID arrays. The MegaRAID Manager utility enables conﬁguration and management of RAID systems while the operating system is running. The MegaRAID Manager utility provides the same feature set as the MegaRAID CU. For information about MegaRAID Manager, refer to Chapter 3, “BIOS Conﬁguration Utility and

MegaRAID Manager.”

1.1.3 WebBIOS Conﬁguration Utility (CTRL+H)

The WebBIOS CU tool provides full-featured, html-based conﬁguration and management of RAID arrays. WebBIOS resides in the BIOS and is independent of the operating system. The WebBIOS CU provides the same feature set as the MegaRAID CU. In addition, it allows you to add drives and migrate between RAID levels. For information about the WebBIOS CU, refer to Chapter 4, “WebBIOS Conﬁguration Utility.”

1.1.4 Power Console Plus Conﬁguration Utility

The Power Console Plus utility provides on-the-ﬂy RAID migration, creating almost limitless adaptability and expansion of any logical drive while the system remains operational. For information about the Power Console Plus utility, refer to Chapter 5, “Start the Power Console

Plus Utility.”

The Power Console Plus utility is an object-oriented GUI utility that conﬁgures and monitors RAID systems locally or over a network. The Power Console Plus manager runs on the Microsoft Windows NT, Windows 2000, Windows XP, and Windows Server 2003 operating systems. With the Power Console Plus manager, you can perform the same tasks as with the MegaRAID Manager.

1-2 Overview

1.2 Operating System Support

Table 1.1 lists the operating system support for each of the

MegaRAID tools.

Table 1.1 MegaRAID Tool Operating System Support

MegaRAID Tool Supported Operating Systems

BIOS CU Operating system (OS) support is not required. The CU

MegaRAID Manager MS-DOS, Novell NetWare, Red Hat Linux, SUSE Linux

WebBIOS CU OS support is not required. The CU runs from the BIOS. Power Console Plus Windows 2000, Windows XP, Windows Server 2003.

runs from the BIOS.

Enterprise Server (SLES).

Note: For information about drivers forthe operating systems, refer

to the MegaRAID Device Driver Installation User’s Guide.

Operating System Support 1-3

1-4 Overview

Chapter 2 Introduction to RAID

This chapter describes RAID features and the advantages that RAID systems offer in terms of fault tolerance, improved I/O performance, and data storage reliability. In addition, it discusses RAID conﬁguration strategies and planning.

This chapter consists of the following sections:

• Section 2.1, “RAID Description”

• Section 2.2, “RAID Beneﬁts”

• Section 2.3, “RAID Functions”

• Section 2.4, “RAID Components and Features”

• Section 2.5, “RAID Levels”

• Section 2.6, “RAID Conﬁguration Strategies”

• Section 2.7, “RAID Availability”

• Section 2.8, “RAID Conﬁguration Planning”

2.1 RAID Description

RAID is an array of multiple independent hard disk drives that provides high performance and fault tolerance. The RAID array appears to the host computer as a single storage unit or as multiple logical units. Data throughput improves because several disks can be accessed simultaneously. RAID systems also improve data storage availability and fault tolerance. Data loss caused by a hard drive failure can be recovered by rebuilding missing data from the remaining data or parity drives.

MegaRAID Conﬁguration Software User’s Guide 2-1

2.2 RAID Beneﬁts

RAID systems improve data storage reliability and fault tolerance compared to single-drive storage systems. Data loss resulting from a hard drive failure can be prevented by reconstructing missing data from the remaining hard drives. RAID has gained popularity because it improves I/O performance and increases storage subsystem reliability.

2.3 RAID Functions

Logical drives, also known as virtual disks, are arrays or spanned arrays that are available to the operating system. The storage space in a logical drive is spread across all the physical drives in the array.

Note: The maximum logical drive size for all supported RAID

Your SCSI hard drives must be organized into logical drives in an array and must be able to support the RAID level that you select. Following are some common RAID functions:

• Creating hot spare drives.

levels (0, 1, 5, 10, and 50) is 2 Tbytes. You can create multiple logical drives on the same physical disks.

• Conﬁguring physical arrays and logical drives.

• Initializing one or more logical drives.

• Accessing controllers, logical drives, and physical drives individually.

• Rebuilding failed hard drives.

• Verifying that the redundancy data in logical drives using RAID level

1, 5, 10, or 50 is correct.

• Reconstructing logical drives after changing RAID levels or adding a

hard drive to an array.

• Selecting a host controller to work on.

2-2 Introduction to RAID

2.4 RAID Components and Features

RAID levels describe a system for ensuring the availability and redundancy of data stored on large disk subsystems. See Section 2.5,

“RAID Levels,” page 2-13 for detailed information about RAID levels.

2.4.1 Physical Array

A physical array is a group of physical disk drives. The physical disk drives are managed in partitions known as logical drives.

2.4.2 Logical Drive

A logical drive is a partition in a physical array of disks that is made up of contiguous data segments on the physical disks. A logical drive can consist of an entire physical array, more than one entire physical array, a part of an array, parts of more than one array, or a combination of any two of these conditions.

Note: The maximum logical drive size for all supported RAID

levels (0, 1, 5, 10, and 50) is 2 Tbytes. You can create multiple logical drives within the same physical array.

2.4.3 RAID Array

A RAID array is one or more logical drives controlled by the RAID controller.

2.4.4 Fault Tolerance

Fault tolerance is the capability of the subsystem to undergo a single failure without compromising data integrity, and processing capability. The RAID controller provides this support through redundant arrays in RAID levels 1, 5, 10 and 50. The system can still work properly even with a single disk failure in an array, through performance can be degraded to some extent.

Note: RAID level 0 is not fault-tolerant. If a drive in a RAID 0 array

RAID Components and Features 2-3

fails, the whole logical drive (all physical drives associated with the logical drive) fails.

Fault tolerance is often associated with system availability because it allows the system to be available during the failures. However, this means it is also important for the system to be available during repair.

A hot spare is an unused physical disk that, in case of a disk failure in a redundant RAID array, can be used to rebuild the data and re-establish redundancy. After the hot spare is automatically moved into the RAID array, the data is automatically rebuilt on the hot spare drive. The RAID array continues to handle requests while the rebuild occurs.

Auto-rebuild allows a failed drive to be replaced and the data automatically rebuilt by hot-swapping the drive in the same drive bay. The RAID array continues to handle requests while the rebuild occurs.

2.4.5 Consistency Check

The Consistency Check operation veriﬁes correctness of the data in logical drives that use RAID levels 1, 5, 10, and 50. (RAID 0 does not provide data redundancy.) For example, in a system with parity, checking consistency means computing the data on one drive and comparing the results to the contents of the parity drive.

Note: LSI recommends that you perform a consistency check at

least once a month.

2.4.6 Background Initialization

Background initialization is a consistency check that is forced when you create a logical drive. The difference between a background initialization and a consistency check is that a background initialization is forced on new logical drives. This is an automatic operation that starts 5 minutes after you create the drive.

Background initialization is a check for media errors on physical drives. It ensures that striped data segments are the same on all physical drives in an array. The background initialization rate is controlled by the rebuild rate set using the BIOS Conﬁguration Utility. The default, and recommended, rate is 30%. Before you change the rebuild rate, you must stop the background initialization or the rate change does not affect the background initialization rate. After you stop background initialization and change the rebuild rate, the rate change takes effect when you restart background initialization.

2-4 Introduction to RAID

2.4.7 Patrol Read

Patrol read involves the review of your system for possible hard drive errors that could lead to drive failure, then action to correct errors. The goal is to protect data integrity by detecting physical drive failure before the failure can damage data. The corrective actions depend on the array conﬁguration and type of errors.

Patrol read starts only when the controller is idle for a deﬁned period of time and no other background tasks are active, though it can continue to run during heavy I/O processes.

You can use the BIOS Configuration Utility to select the patrol read options, which you can use to set automatic or manual operation, or disable patrol read. Perform the following steps to select a patrol read option:

Step 1. Select Objects → Adapter from the Management Menu.

Step 2. Select Patrol Read Options from the Adapter menu. Step 3. The following options display:

The Adapter menu displays.

Patrol Read Mode Patrol Read Status Patrol Read Control

Step 4. Select Patrol Read Mode to display the patrol read options:

Manual – In manual mode, you must initiate the patrol read. Auto – In auto mode, the ﬁrmware initiates the patrol read on a

scheduled basis. Manual Halt – Use manual halt to stop the automatic operation,

then switch to manual mode. Disable – Use this option to disable the patrol read.

Step 5. If you use Manual mode, perform the following steps to initiate

a patrol read: a. Select Patrol Read Control and press ENTER. b. Select Start and press ENTER.

Note. Pause/Resume is not a valid operation when Patrol Read

is set to Manual mode.

RAID Components and Features 2-5

Step 6. Select Patrol Read Status to display the number of iterations

2.4.8 Disk Striping

Disk striping allows you to write data across multiple physical disks instead of just one physical disk. Disk striping involves partitioning each drive storage space into stripes that can vary in size from 8 Kbytes to 128 Kbytes. These stripes are interleaved in a repeated sequential manner. The combined storage space is composed of stripes from each drive. It is recommended that you keep stripe sizes the same across RAID arrays.

For example, in a four-disk system using only disk striping (used in RAID level 0), segment 1 is written to disk 1, segment 2 is written to disk 2, and so on. Disk striping enhances performance because multiple drives are accessed simultaneously, but disk striping does not provide data redundancy.

Figure 2.1 shows an example of disk striping.

completed, the current state of the patrol read (active or stopped), and the schedule for the next execution of patrol read.

Note: Do not install an operating system on a logical drive with

less than a 16 Kbyte stripe size.

Figure 2.1 Disk Striping (RAID 0) Example

Segment 1 Segment 5 Segment 9

2.4.8.1 Stripe Width

Stripe width is the number of disks involved in an array where striping is implemented. For example, a four-disk array with disk striping has a stripe width of four.

2-6 Introduction to RAID

Segment 2 Segment 6

Segment 10

Segment 3 Segment 7

Segment 11

Segment 4 Segment 8

Segment 12

2.4.8.2 Stripe Size

The stripe size is the length of the interleaved data segments that the RAID controller writes across multiple drives.

2.4.9 Disk Mirroring

With disk mirroring (used in RAID 1), data written to one disk is simultaneously written to another disk. If one disk fails, the contents of the other disk can be used to run the system and reconstruct the failed disk. The primary advantage of disk mirroring is that it provides 100% data redundancy. Because the disk contents are completely written to a second disk, it does not matter whether one of the disks fails. Both disks contain the same data at all times. Either drive can act as the operational drive.

Disk mirroring provides 100% redundancy, but is expensive because each drive in the system must be duplicated. Figure 2.2 shows an example of disk mirroring.

Figure 2.2 Disk Mirroring (RAID 1) Example

2.4.10 Parity

Segment 1 Segment 2 Segment 3 Segment 4 Segment 4 Duplicated

Segment 1 Duplicated Segment 2 Duplicated Segment 3 Duplicated

Parity generates a set of redundancy data from two or more parent data sets. The redundancy data can reconstruct one of the parent data sets. Parity data does not fully duplicate the parent data sets. In RAID, this method is applied to entire drives or stripes across all disk drives in an array. The types of parity are described in Table 2.1.

RAID Components and Features 2-7

Table 2.1 Types of Parity

Parity Type Description

Dedicated The parity of the data on two or more disk drives is stored on

Distributed The parity data is distributed across more than one drive in the

an additional disk.

system.

If a single disk drive fails, it can be rebuilt from the parity and the data on the remaining drives. RAID level 5 combines distributed parity with disk striping, as shown in Figure 2.3. Parity provides redundancy for one drive failure without duplicating the contents of entire disk drives, but parity generation can slow the write process.

Figure 2.3 Distributed Parity (RAID 5) Example

Segment 1 Segment 7

Parity (9–12)

Note: Parity is distributed across multiple drives in the array.

Segment 2 Segment 8

Segment 3 Segment 9

Parity (5–8)

Segment 4

Segment 10

2.4.11 Disk Spanning

Segment 5 Segment 11 Parity (1–4)

Segment 6

Segment 12

Disk spanning allows multiple physical drives to function like one big drive. Disk spanning overcomes lack of disk space and simpliﬁes storage management by combining existing resources or adding relatively inexpensive resources. For example, four 20 Gbyte drives can be combined to appear to the operating system as a single 80 Gbyte drive.

Spanning alone does not provide reliability or performance enhancements. Spanned logical drives must have the same stripe size and must be contiguous. In Figure 2.4, RAID 1 arrays are turned into a RAID 10 array.

Important: Make sure that the spans are in different backplanes, so

that if one span fails, you do not lose the whole array.

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