LSI MegaRAID Enterprise 1600 User Manual
MegaRAID Enterprise 1600
Hardware Guide
MAN-471
6/12/01
© Copyright 2001 LSI Logic Corporation
All rights reserved.
LSI Logic Corporation
6145-D Northbelt Parkway
Norcross, GA 30071
This publication contains proprietary information which is protected by copyright. No part of this publication can be reproduced, transcribed,
stored in a retrieval system, translated into any language or computer language, or transmitted in any form whatsoever without the prior written
consent of the publisher, LSI Logic Corporation. LSI Logic Corporation acknowledges the following trademarks:
Intel is a registered trademark of Intel Corporation
Sytos Plus is a registered trademark of Sytron Corporation.
MS-DOS, and Microsoft are registered trademarks of Microsoft Corporation. Windows 95, Microsoft Windows and Windows NT are trademarks
of Microsoft Corporation.
MegaRAID is a registered trademark of LSI Logic Corporation.
SCO, UnixWare, and Unix are registered trademarks of the Santa Cruz Operation. Inc.
Novell NetWare is a registered trademark of Novell Corporation.
IBM, AT, VGA, PS/2, and OS/2 are registered trademarks and XT and CGA are trademarks of International Business Machines Corporation.
.
Revision History
3/20/00 Initial release.
2/23/01 Corrected RAID 0 graphic in Chapter 3, and Array Configuration Planner table in Chapter 5.
4/13/01 Added Chapter 7 Cluster Configuration and Installation, and Appendix C Cluster Configuration with a Crossover
Cable.
6/12/01 Make corrections, such as cache size (16 MB is smallest option), and the number of physical disk drives supported at
various RAID levels.
MegaRAID Enterprise 1600 Hardware Guide
ii
Table of Contents
1 Overview................................................... 1
Single Ended and Differential SCSI Buses....................... 2
Maximum Cable Length for SCSI Standards....................2
Documentation Set............................................................3
2 Introduction to RAID................................ 5
RAID Overview................................................................ 5
RAID Levels..................................................................... 6
Consistency Check............................................................6
Fault Tolerance ................................................................. 6
Disk Striping..................................................................... 7
Disk Mirroring..................................................................8
Disk Spanning...................................................................9
Parity...............................................................................10
Hot Spares.......................................................................11
Disk Rebuild ................................................................... 12
Logical Drive..................................................................13
Hot Swap ........................................................................13
SCSI Drive States ...........................................................13
Logical Drive States........................................................13
Disk Array Types............................................................14
Enclosure Management................................................... 14
3 RAID Levels ............................................ 15
Selecting a RAID Level..................................................16
RAID 0 ...........................................................................17
RAID 1 ...........................................................................18
RAID 3 ...........................................................................19
RAID 5 ...........................................................................21
RAID 10 .........................................................................22
RAID 30 .........................................................................23
RAID 50 .........................................................................24
4 Features..................................................25
SMART Technology.......................................................25
Configuration on Disk.....................................................26
Hardware Requirements..................................................26
Configuration Features....................................................26
Hardware Architecture Features .....................................27
Array Performance Features ...........................................27
RAID Management Features...........................................28
Fault Tolerance Features.................................................28
Software Utilities............................................................ 28
Operating System Software Drivers................................29
MegaRAID Specifications..............................................29
Components.................................................................... 30
Summary.........................................................................32
Preface
iii
Table of Contents,
Continued
5 Configuring MegaRAID.......................... 33
Configuring SCSI Physical Drives..................................33
Current Configuration.....................................................34
Logical Drive Configuration...........................................36
Physical Device Layout ..................................................37
Configuring Arrays .........................................................39
Configuration Strategies .................................................40
Assigning RAID Levels.................................................. 42
Configuring Logical Drives ............................................ 42
Optimizing Data Storage.................................................43
Planning the Array Configuration...................................44
Array Configuration Planner...........................................45
6 Hardware Installation ............................47
Checklist ......................................................................... 48
Installation Steps.............................................................49
Step 1 Unpack................................................................. 50
Step 2 Power Down ........................................................50
Step 3 Configure Motherboard .......................................50
Step 4 Install Cache Memory..........................................51
Step 5 Set Jumpers.......................................................... 53
Step 6 Set Termination ...................................................56
SCSI Termination ........................................................... 57
Step 7 Set SCSI Terminator Power.................................61
Step 8 Connect Battery Pack (Optional).........................62
Step 9 Install MegaRAID Card.......................................66
Step 10 Connect SCSI Cables.........................................67
Step 11 Set Target IDs....................................................69
Step 12 Power Up ........................................................... 71
Step 13 Run MegaRAID Configuration Utility...............71
Step 14 Install the Operating System Driver...................72
Summary.........................................................................73
MegaRAID Enterprise 1600 Hardware Guide
iv
Table of Contents,
Continued
7 Cluster Installation and Configuration. 75
Software Requirements................................................... 75
Hardware Requirements..................................................76
Installation and Configuration ........................................77
Driver Installation Instructions under Microsoft
Windows 2000 Advanced Server....................................78
Network Requirements ...................................................83
Shared Disk Requirements.............................................. 83
Cluster Installation.......................................................... 84
Installing the Windows 2000 Operating System............. 85
Setting Up Networks.......................................................85
Configuring the Cluster Node Network Adapter.............87
Configuring the Public Network Adapter .......................88
Verifying Connectivity and Name Resolution ................ 88
Verifying Domain Membership ......................................89
Setting Up a Cluster User Account .................................90
Setting Up Shared Disks.................................................91
Configuring Shared Disks...............................................92
Assigning Drive Letters ..................................................92
Verifying Disk Access and Functionality........................93
Cluster Service Software Installation.............................. 94
Configuring Cluster Disks...............................................97
Validating the Cluster Installation ................................103
Configuring the Second Node....................................... 103
Verify Installation.........................................................104
SCSI Drive Installations ............................................... 105
Configuring the SCSI Devices...................................... 105
Terminating the Shared SCSI Bus ................................105
8 Troubleshooting .................................. 107
BIOS Boot Error Messages ..........................................109
Other BIOS Error Messages .........................................111
DOS ASPI Driver Error Messages ...............................112
Other Potential Problems..............................................113
A SCSI Cables and Connectors .............115
SCSI Connectors...........................................................115
68-Pin High Density SCSI Internal Connectors............ 115
68-Pin Connector Pinout for Single-Ended SCSI .........121
68-Pin Connector Pinout for Low-Voltage Differential SCSI 123
B Audible Warnings ................................ 125
C Cluster Configuration with a Crossover Cable 127
Solution.........................................................................128
Glossary .......................................................... 129
Index ................................................................ 137
Preface
v
Preface
The MegaRAID Enterprise 1600 64-Bit 160M (Low Voltage Differential SCSI) I2O PCI Disk Array
Controller supports four Ultra and Wide SCSI channels with data transfer rates up to 160 MB/s. This manual
describes the MegaRAID Enterprise 1600 64-Bit 160M controller.
Limited Warranty
Limitations of Liability
The buyer agrees if this product proves to be defective, that LSI Logic Corporation is obligated only to repair
or replace this product at LSI Logic’s discretion according to the terms and conditions of the warranty
registration card that accompanies this product. LSI Logic shall not be liable in tort or contract for any loss or
damage, direct, incidental or consequential resulting from the use of this product. Please see the Warranty
Registration Card shipped with this product for full warranty details.
whatsoever, whether direct, indirect, incidental, or consequential (whether arising from the design or use of
this product or the support materials provided with the product). No action or proceeding against LSI Logic
may be commenced more than two years after the delivery of product to Licensee of Licensed Software.
Licensee agrees to defend and indemnify LSI Logic from any and all claims, suits, and liabilities (including
attorney’s fees) arising out of or resulting from any actual or alleged act or omission on the part of Licensee,
its authorized third parties, employees, or agents, in connection with the distribution of Licensed Software to
end-users, including, without limitation, claims, suits, and liability for bodily or other injuries to end-users
resulting from use of Licensee’s product not caused solely by faults in Licensed Software as provided by LSI
Logic to Licensee.
LSI Logic Corporation shall in no event be held liable for any loss, expenses, or damages of any kind
Cont’d
MegaRAID Enterprise 1600 Hardware Guide
vi
Preface,
Continued
Package Contents
Technical Support
Web Site
You should have received:
• a MegaRAID Enterprise 1600 64-Bit 160M Controller
• a CD with drivers, utilities, and documentation
• a MegaRAID Enterprise 1600 Hardware Guide
• a MegaRAID Configuration Software Guide
• a MegaRAID Operating System Drivers Guide
• software license agreement
• warranty registration card
If you need help installing, configuring, or running the MegaRAID Controller, call LSI Logic
Technical Support at 678-728-1250. Before you call, please complete the MegaRAID Problem
Report form on the next page.
We invite you to access the LSI Logic world wide web site at:
http://www.lsil.com.
Preface
vii
MegaRAID Problem Report Form
Customer Information MegaRAID Information
Name Today’s Date
Company Date of Purchase
Address Invoice Number
City/State Serial Number
Country Number of Channels
email address Cache Memory
Phone Firmware Version
Fax BIOS Version
System Information
Motherboard: BIOS manufacturer:
Operating System: BIOS Date:
Op. Sys. Ver.: Video Adapter:
MegaRAID
Driver Ver.:
Network Card: System Memory:
Other disk controllers
installed:
Description of problem:
Steps necessary to re-create problem:
1.
CPU Type/Speed:
Other adapter cards
installed:
2.
3.
4.
MegaRAID Enterprise 1600 Hardware Guide
viii
Logical Drive Configuration
Logical
Drive
LD0
LD1
LD2
LD3
LD4
LD5
LD6
LD7
LD8
LD9
LD10
LD11
LD12
LD13
LD14
LD15
LD16
LD17
LD18
LD19
LD20
LD21
LD22
LD23
LD24
LD25
LD26
LD27
LD28
LD29
LD30
LD31
LD32
LD33
LD34
LD35
LD36
LD37
LD38
LD39
RAID
Level
Stripe
Size
Logical Drive
Size
Cache
Policy
Read
Policy
Write
Policy
# of
Physical
Drives
Preface
ix
Physical Device Layout
Target ID
Device Type
Logical Drive Number/
Drive Number
Manufacturer/Model
Number
Firmware level
Target ID
Device Type
Logical Drive Number/
Drive Number
Manufacturer/Model
Number
Firmware level
Target ID
Device Type
Logical Drive Number/
Drive Number
Manufacturer/Model
Number
Firmware level
Target ID
Device Type
Logical Drive Number/
Drive Number
Manufacturer/Model
Number
Firmware level
Target ID
Device Type
Logical Drive Number/
Drive Number
Manufacturer/Model
Number
Firmware level
Target ID
Device Type
Logical Drive Number/
Drive Number
Manufacturer/Model
Number
Firmware level
Target ID
Device Type
Logical Drive Number/
Drive Number
Manufacturer/Model
Number
Firmware level
Target ID
Device Type
Channel A Channel B Channel C Channel D
MegaRAID Enterprise 1600 Hardware Guide
x
Logical Drive Number/
Drive Number
Manufacturer/Model
Number
Firmware level
Target ID
Device Type
Logical Drive Number/
Drive Number
Manufacturer/Model
Number
Firmware level
Target ID
Device Type
Logical Drive Number/
Drive Number
Manufacturer/Model
Number
Firmware level
Target ID
Device Type
Logical Drive Number/
Drive Number
Manufacturer/Model
Number
Firmware level
Target ID
Device Type
Logical Drive Number/
Drive Number
Manufacturer/Model
Number
Firmware level
Target ID
Device Type
Logical Drive Number/
Drive Number
Manufacturer/Model
Number
Firmware level
Target ID
Device Type
Logical Drive Number/
Drive Number
Manufacturer/Model
Number
Firmware level
Target ID
Device Type
Logical Drive Number/
Drive Number
Manufacturer/Model
Number
Firmware level
Channel A Channel B Channel C Channel D
Preface
xi
Disclaimer
Disclaimer
This manual describes the operation of the LSI Logic MegaRAID Controller. Although efforts have been made to assure
the accuracy of the information contained here, LSI Logic expressly disclaims liability for any error in this information,
and for damages, whether direct, indirect, special, exemplary, consequential or otherwise, that may result from such error,
including but not limited to the loss of profits resulting from the use or misuse of the manual or information contained
therein (even if LSI Logic has been advised of the possibility of such damages). Any questions or comments regarding this
document or its contents should be addressed to LSI Logic at the address shown on the cover.
LSI Logic provides this publication “as is” without warranty of any kind, either expressed or implied, including, but not
limited to, the implied warranties of merchantability or fitness for a specific purpose.
Some states do not allow disclaimer of express or implied warranties or the limitation or exclusion of liability for indirect,
special, exemplary, incidental or consequential damages in certain transactions; therefore, this statement may not apply to
you. Also, you may have other rights which vary from jurisdiction to jurisdiction.
This publication could include technical inaccuracies or typographical errors. Changes are periodically made to the
information herein; these changes will be incorporated in new editions of the publication. LSI Logic may make
improvements and/or revisions in the product(s) and/or the program(s) described in this publication at any time.
Requests for technical information about LSI Logic products should be made to your LSI Logic authorized reseller or
marketing representative.
MegaRAID Enterprise 1600 Hardware Guide
xii
FCC Regulatory Statement
This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) this
device may not cause harmful interference, and (2) this device must accept any interference received, including
interference that may cause undesired operation.
Warning:
compliance could void the user's authority to operate the equipment.
Note:
Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in
a residential installation. This equipment generates, uses and can radiate radio frequency energy and, if not installed
and used in accordance with the instructions, may cause harmful interference to radio communications. However,
there is no guarantee that interference will not occur in a specific installation. If this equipment does cause harmful
interference to radio or television reception, which can be determined by turning the equipment off and on, try to
correct the interference by one or more of the following measures:
1) Reorient or relocate the receiving antenna.
2) Increase the separation between the equipment and the receiver.
3) Connect the equipment into an outlet on a circuit different from
4) Consult the dealer or an experienced radio/TV technician for help.
Shielded interface cables must be used with this product to ensure compliance with the Class B FCC limits.
LSI Logic Corporation MegaRAID Enterprise 1600 64-Bit 160M PCI SCSI Disk Array Controller
Model Number:
FCC ID Number:
Changes or modifications to this unit not expressly approved by the party responsible for
This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to
that to which the receiver is connected.
Series 471
IUESER471
Disclaimer
LSI Logic certifies only that this product will work correctly when this
product is used with the same jumper settings, the same system
configuration, the same memory module parts, and the same
peripherals that were tested by LSI Logic with this product. The
complete list of tested jumper settings, system configurations,
peripheral devices, and memory modules are documented in the LSI
Logic Compatibility Report for this product. Call your LSI Logic sales
representative for a copy of the Compatibility Report for this product.
Preface
xiii
MegaRAID Enterprise 1600 Hardware Guide
xiv
1Overview
The MegaRAID® Enterprise 1600 LVD (Low Voltage Differential SCSI) PCI RAID controller
adapter card provides four SCSI channels. Using LVD, you can use cables up to 25 meters long.
Throughput on each SCSI channel can be as high as 160 MB/s. MegaRAID supports both a low
voltage differential SCSI bus or a single ended SCSI bus.
MegaRAID Enterprise 1600 64-Bit LVD is a high performance intelligent PCI-to-SCSI host
adapter with RAID control capabilities. MegaRAID Enterprise 1600 64-Bit LVD requires no
special motherboard PCI expansion slot. The MegaRAID Enterprise 1600 card includes an Intel
i960RN processor. MegaRAID provides reliability, high performance, and fault-tolerant disk
subsystem management.
SCSI Channels
NVRAM and Flash ROM
SCSI Connectors
MegaRAID Enterprise 1600 64-Bit LVD has four 160M SCSI channels. There are two QLogic
dual SCSI controllers, each supporting two of the four channels. Each SCSI channel supports up to
fifteen non-Ultra SCSI devices.
stored in flash memory for easy upgrade.
MegaRAID has four ultra high density 68-pin external SCSI connectors and two 68-pin internal
SCSI connectors for internal SCSI drives.
A 32 KB x 8 NVRAM stores RAID system configuration information. The firmware is
Chapter 1 Overview
1
Single Ended and Differential SCSI Buses
The SCSI standard defines two electrical buses:
• a single ended bus
• a differential bus
Maximum Cable Length for SCSI Standards
Standard Single ended LVD Maximum Number
SCSI I 6 m 12 m 7
Fast SCSI 6 m 12 m 7
Fast Wide SCSI 6 m 12 m 15
Ultra SCSI 1.5 m 12 m 7
Ultra SCSI 3 m 12 m 3
Wide Ultra SCSI 12 m 15
Wide Ultra SCSI 1.5 m 12 m 7
Wide Ultra SCSI 3 m 12 m 3
Ultra2 SCSI 25 m 1
Ultra2 SCSI 12 m 7
Wide Ultra2 SCSI 25 m 1
Wide Ultra2 SCSI 12 m 15
Maximum cable length for 160M
of Drives
Standard Single-ended LVD Maximum # of Drives
160M SCSI 25M 1
160M SCSI 12M 7
Wide 160M SCSI 25M 1
Wide 160M SCSI 12M 15
SCSI Bus Widths and Maximum Throughput
SCSI Standard SCSI Bus Width SCSI Throughput
SCSI I 8 bits 5 MB/s
Fast SCSI 8 bits 10 MB/s
Fast Wide SCSI 16 bits 20 MB/s
Ultra SCSI 8 bits 20 MB/s
Wide Ultra SCSI 16 bits 40 MB/s
Ultra2 SCSI 8 bits 40 MB/s
Wide Ultra2 SCSI 16 bits 80 MB/s
160M SCSI 8 bits 80 MB/s
Wide 160M SCSI 16 bits 160 MB/s
MegaRAID Enterprise 1600 Hardware Guide
2
Documentation Set
The MegaRAID Enterprise 1600 64-Bit LVD technical documentation set includes:
• the MegaRAID Enterprise 1600 Hardware Guide
• the MegaRAID Configuration Software Guide
• the WebBIOS Guide
• the MegaRAID Operating System Drivers Guide
Using MegaRAID Enterprise 1600 Manuals
The MegaRAID Enterprise 1600 Hardware Guide includes a RAID
overview, RAID planning, and RAID system configuration information. Read it first.
MegaRAID Configuration Software Guide This manual describes the MegaRAID software utilities that configure
and modify RAID systems. The software utilities include:
• MegaRAID Configuration Utility
• MegaRAID Manager
• Power Console Plus
WebBIOS Guide This manual explains the operation of the WebBIOS Configuration Utility. WebBIOS allows you
to configure and manage RAID systems running in remote servers.
MegaRAID Operating System Drivers Guide This manual provides detailed information about the operating system
drivers.
Chapter 1 Overview
3
MegaRAID Enterprise 1600 Hardware Guide
4
2 Introduction to RAID
RAID (Redundant Array of Independent Disks) is an array of multiple independent hard disk
drives that provide high performance and fault tolerance. A RAID disk subsystem improves I/O
performance. The RAID array appears to the host computer as a single storage unit or as multiple
logical units. I/O is faster because drives can be accessed simultaneously. RAID improves data
storage reliability and fault tolerance. You can prevent data loss caused by drive failure by
reconstructing missing data from the remaining data and parity drives.
RAID Overview
The following topics are discussed:
• RAID levels on page 6
• Consistency check on page 6
• Fault tolerance on page 6
• Disk striping on page 7
• Disk mirroring on page 8
• Disk spanning on page 8
• Parity on page 10
• Hot spares on page 11
• Disk rebuilds on page 12
• Logical drives on page 13
• Hot swap on page 13
• SCSI drive states on page 13
• Logical drive states on page 13
• Disk array types on page 14
• Enclosure management on page 14
Chapter 2 Introduction to RAID
5
RAID Levels
RAID (Redundant Array of Independent Disks) is a collection of specifications that describe a
system for ensuring the reliability and stability of data stored on large disk subsystems. A RAID
system can be implemented in a number of different versions (or RAID Levels). The standard
RAID levels are 0, 1, 3, and 5. MegaRAID supports all standard RAID levels and RAID levels 10,
30, and 50, special RAID versions supported by MegaRAID.
Consistency Check
In RAID, check consistency verifies the correctness of redundant data in an array. For example, in
a system with dedicated parity, checking consistency means computing the parity of the data drives
and comparing the results to the contents of the dedicated parity drive.
Fault Tolerance
Fault tolerance is achieved through cooling fans, power supplies, and the ability to hot swap drives.
MegaRAID provides hot swapping through the hot spare feature. A hot spare drive is an unused
online available drive. MegaRAID can instantly rebuild a logical drive using a hot spare.
After the hot spare is automatically moved into the RAID subsystem, the failed drive can be
automatically rebuilt. The RAID disk array continues to handle requests while the rebuild occurs.
MegaRAID Enterprise 1600 Hardware Guide
6
Disk Striping
Disk striping writes data across multiple disk drives instead of just one disk drive. Disk striping
involves partitioning each drive storage space into stripes that can vary in size from 2 KB to 128
KB. These stripes are interleaved in a repeated sequential manner. The combined storage space is
composed of stripes from each drive. MegaRAID supports stripe sizes of 2 KB, 4 KB, 8 KB, 16
KB, 32 KB, 64 KB, or 128 KB. For example, in a four-disk system using only disk striping (as 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.
Stripe Width
Stripe Size
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.
The stripe size is the length of the interleaved data segments that MegaRAID writes across
multiple drives. MegaRAID supports stripe sizes of 2 KB, 4 KB, 8 KB, 16 KB, 32 KB, 64 KB, or
128 KB.
Chapter 2 Introduction to RAID
7
Disk Mirroring
With mirroring (used in RAID 1), data written to one disk drive is simultaneously written to
another disk drive. If one disk drive fails, the contents of the other disk drive can be used to run the
system and reconstruct the failed drive. The primary advantage of disk mirroring is that it provides
100% data redundancy. Since the contents of the disk drive are completely written to a second
drive, it does not matter if one of the drives fails. Both drives 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.
MegaRAID Enterprise 1600 Hardware Guide
8
Disk Spanning
Disk spanning allows multiple disk drives to function like one big drive. Spanning overcomes lack
of disk space and simplifies storage management by combining existing resources or adding
relatively inexpensive resources. For example, four 400 MB disk drives can be combined to appear
to the operating system as one single 1600 MB drive.
Spanning alone does not provide reliability or performance enhancements. Spanned logical drives
must have the same stripe size and must be contiguous. In the following graphic, RAID 1 array is
turned into a RAID 10 array.
This controller supports a span depth of eight. That means that eight RAID 1, 3 or 5 arrays can be
spanned to create one logical drive.
Spanning for RAID 10, RAID 30, or RAID 50
Level Description
10 Configure RAID 10 by spanning two contiguous RAID 1 logical drives.
The RAID 1 logical drives must have the same stripe size.
30 Configure RAID 30 by spanning two contiguous RAID 3 logical drives.
The RAID 3 logical drives must have the same stripe size.
50 Configure RAID 50 by spanning two contiguous RAID 5 logical drives.
The RAID 5 logical drives must have the same stripe size.
Note:
Chapter 2 Introduction to RAID
Spanning two contiguous RAID 0 logical drives does not produce a new
RAID level or add fault tolerance. It does increase the size of the logical
volume and improves performance by doubling the number of spindles.
9
Parity
Parity generates a set of redundancy data from two or more parent data sets. The redundancy data
can be used to 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. A dedicated parity scheme during normal read/write operations is shown below. The
types of parity are:
Type Description
Dedicated Parity The parity of the data on two or more disk drives is
stored on an additional disk.
Distributed
Parity
The parity data is distributed across all drives in the
system.
If a single disk drive fails, it can be rebuilt from the parity and the data on the remaining drives.
RAID level 3 combines dedicated parity with disk striping. The parity disk in RAID 3 is the last
physical drive in a RAID set.
RAID level 5 combines distributed parity with disk striping. Parity provides redundancy for one
drive failure without duplicating the contents of entire disk drives, but parity generation can slow
the write process.
MegaRAID Enterprise 1600 Hardware Guide
10
Hot Spares
A hot spare is an extra, unused disk drive that is part of the disk subsystem. It is usually in standby
mode, ready for service if a drive fails. Hot spares permit you to replace failed drives without
system shutdown or user intervention.
MegaRAID implements automatic and transparent rebuilds using hot spare drives, providing a high
degree of fault tolerance and zero downtime. MegaRAID RAID Management software allows you
to specify physical drives as hot spares. When a hot spare is needed, the MegaRAID controller
assigns the hot spare that has a capacity closest to and at least as great as that of the failed drive to
take the place of the failed drive.
Important
Hot spares are employed only in arrays with redundancy, for
example, RAID levels 1, 3, 5, 10, 30, and 50.
A hot spare connected to a specific MegaRAID controller can
only be used to rebuild a drive that is connected to the same
controller.
Chapter 2 Introduction to RAID
11
Disk Rebuild
You rebuild a disk drive by recreating the data that had been stored on the drive before the drive
failed.
Rebuilding can be done only in arrays with data redundancy such as RAID level 1, 3, 5, 10, 30,
and 50.
Standby (warm spare) rebuild is employed in a mirrored (RAID 1) system. If a disk drive fails, an
identical drive is immediately available. The primary data source disk drive is the original disk
drive.
A hot spare can be used to rebuild disk drives in RAID 1, 3, 5, 10, 30, or 50 systems. If a hot spare
is not available, the failed disk drive must be replaced with a new disk drive so that the data on the
failed drive can be rebuilt.
Using hot spares, MegaRAID can automatically and transparently rebuild failed drives with userdefined rebuild rates. If a hot spare is available, the rebuild can start automatically when a drive
fails. MegaRAID automatically restarts the system and the rebuild if the system goes down during
a rebuild.
Rebuild Rate
Physical Array
The rebuild rate is the fraction of the compute cycles dedicated to rebuilding failed drives. A
rebuild rate of 100 percent means the system is totally dedicated to rebuilding the failed drive.
The rebuild rate can be configured between 0% and 100%. At 0%, the rebuild is only done if the
system is not doing anything else. At 100%, the rebuild has a higher priority than any other system
activity.
A RAID array is a collection of physical disk drives governed by the RAID management software.
A RAID array appears to the host computer as one or more logical drives.
MegaRAID Enterprise 1600 Hardware Guide
12
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 any of the following:
• an entire physical array
• more than one entire physical array
• a part of an array
• parts of more than one array
•
a combination of any two of the above conditions
Hot Swap
A hot swap is the manual replacement of a defective physical disk unit while the computer is still
running. When a new drive has been installed, you must issue a command to rebuild the drive.
MegaRAID can be configured to detect the new disks and to rebuild the contents of the disk drive
automatically.
SCSI Drive States
A SCSI disk drive can be in one of these states:
(ONLIN)
(READY)
Hot Spare
(HOTSP)
State Description
Online
Ready
Fail
(FAIL)
Rebuild
(REB)
The drive is functioning normally and is a part of a configured
logical drive.
The drive is functioning normally but is not part of a configured
logical drive and is not designated as a hot spare.
The drive is powered up and ready for use as a spare in case an
online drive fails.
A fault has occurred in the drive placing it out of service.
The drive is being rebuilt with data from a failed drive.
Logical Drive States
State Description
Optimal The drive operating condition is good. All configured drives are
online
Degraded The drive operating condition is not optimal. One of the
configured drives has failed or is offline.
Failed The drive has failed.
Offline The drive is not available to MegaRAID.
Chapter 2 Introduction to RAID
13
Disk Array Types
The RAID disk array types are:
Type Description
Software-
Based
SCSI to SCSI The array controller resides outside of the host computer and
Bus-Based The array controller resides on the bus (for example, a PCI or
Enclosure Management
The array is managed by software running in a host computer using
the host CPU bandwidth. The disadvantages associated with this
method are the load on the host CPU and the need for different
software for each operating system.
communicates with the host through a SCSI adapter in the host.
The array management software runs in the controller. It is
transparent to the host and independent of the host operating
system. The disadvantage is the limited data transfer rate of the
SCSI channel between the SCSI adapter and the array controller.
EISA bus) in the host computer and has its own CPU to generate
the parity and handle other RAID functions. A bus-based controller
can transfer data at the speed of the host bus (PCI, ISA, EISA, VLBus) but is limited to the bus it is designed for. MegaRAID resides
on a PCI bus, which can handle data transfer at up to 528 MB/s.
With MegaRAID, each channel can handle data transfer rates up to
160 MB/s per SCSI channel.
Enclosure management is the intelligent monitoring of the disk subsystem by software and/or
hardware.
The disk subsystem can be part of the host computer or separate from it. Enclosure management
helps you stay informed of events in the disk subsystem, such as a drive or power supply failure.
Enclosure management increases the fault tolerance of the disk subsystem.
MegaRAID Enterprise 1600 Hardware Guide
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3 RAID Levels
There are six official RAID levels (RAID 0 through RAID 5). MegaRAID supports RAID levels 0,
1, 3, and 5. LSI Logic has designed three additional RAID levels (10, 30, and 50) that provide
additional benefits. The RAID levels that MegaRAID supports are:
RAID Level Type turn to
0 Standard page 17
1 Standard page 18
3 Standard page 19
5 Standard page 21
10 MegaRAID only page 22
30 MegaRAID only page 23
50 MegaRAID only page 24
Select RAID Level
To ensure the best performance, you should select the optimal RAID level when you create a
system drive. The optimal RAID level for your disk array depends on a number of factors:
• the number of drives in the disk array
• the capacity of the drives in the array
• the need for data redundancy
• the disk performance requirements
Selecting a RAID Level
The factors you need to consider when selecting a RAID level are listed on the next page.
Chapter 3 RAID Levels
15
Selecting a RAID Level
The factors you need to consider when selecting a RAID level are listed below.
Level Description and
Use
0 Data divided in
blocks and
distributed
sequentially (pure
striping). Use for
non-critical data
that requires high
performance.
1 Data duplicated on
another disk
(mirroring). Use
for read-intensive
fault-tolerant
systems
3 Disk striping with a
dedicated parity
drive. Use for noninteractive apps
that process large
files sequentially.
5 Disk striping and
parity data across
all drives. Use for
high read volume
but low write
volume, such as
transaction
processing.
10 Data striping and
mirrored drives.
30 Disk striping with a
dedicated parity
drive.
50 Disk striping and
parity data across
all drives.
Pros Cons Maximum
Physical
High data
throughput
for large
files
100% data
redundancy
Achieves
data
redundancy
at low cost
Achieves
data
redundancy
at low cost
High data
transfers,
complete
redundancy
High data
transfers,
redundancy
High data
transfers,
redundancy
No fault
tolerance. All
data lost if
any drive
fails.
Doubles disk
space.
Reduced
performance
during
rebuilds.
Performance
not as good as
RAID 1
Performance
not as good as
RAID 1
More
complicated
More
complicated
More
complicated
One to 32 No
Three to 32 Yes
Three to 32 Yes
Four to 32
(must be a
multiple of
Six to 32 Yes
Six to 32 Yes
Fault
Tolerant
Drives
Two Yes
Yes
two)
MegaRAID Enterprise 1600 Hardware Guide
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