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SA33-3285-02
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Compex Systems SA33-3285-02 User Manual

Advanced SerialRAID Adapters
User’s Guide and Maintenance Information
SA33-3285-02
Advanced SerialRAID Adapters
User’s Guide and Maintenance Information
SA33-3285-02
Third Edition (September 2000)
This softcopy of 14 January 2002 is a minor revision to SA33-3285-02. It contains new technical changes that are not shown in the printed book. Such changes are shown by a colon (:) to the left of each change. Changes that are also in the printed book are shown by a vertical line to the left of each change.
THIS PUBLICATION IS PRINTED “AS IS” WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Some states do not allow disclaimer of express or implied warranties in certain transactions; therefore, this statement may not apply to you.
This publication could contain technical inaccuracies or typographical errors. Changes are periodically made to the information herein; these changes will be incorporated in new editions of the publication.
It is possible that this publication may contain reference to, or information about, products (machines and programs), programming, or services that are not announced in your country. Such references or information must not be construed to mean that such products, programming, or services will be offered in your country. Any reference to a licensed program in this publication is not intended to state or imply that you can use only the licensed program indicated. You can use any functionally equivalent program instead.
© Copyright International Business Machines Corporation 1996, 2000. All rights reserved.
Note to U.S. Government Users — Documentation related to restricted rights — Use, duplication, or disclosure is subject to restrictions set forth in the GSA ADP Schedule Contract.

Contents

Safety Notices........................xv
Definitions of Safety Notices ...................xv
Safety Notice for Installing, Relocating, or Servicing............xv
About This Book ......................xvii
Who Should Use This Book ...................xvii
What This Book Contains ....................xvii
If You Need More Information...................xvii
||
Part 1. User Information ........................1
Web Support Pages......................xviii
Numbering Convention.....................xviii
Chapter 1. Introducing SSA and the Advanced SerialRAID Adapters .....3
Serial Storage Architecture (SSA) ..................3
The Advanced SerialRAID Adapters (type 4–P).............4
Fast-Write Cache Feature ...................5
128 MB Memory Module Feature .................5
Lights of the Advanced SerialRAID Adapters .............6
Port Addresses of the Advanced SerialRAID Adapters ..........6
SSA Adapter ID during Bring-Up ..................6
Chapter 2. Introducing SSA Loops .................7
Loops, Links, and Data Paths ...................7
Simple Loop ........................8
Simple Loop — One Disk Drive Missing ...............9
Simple Loop — Two Disk Drives Missing ..............10
One Loop with Two Adapters in One Using System...........11
One Loop with Two Adapters in Each of Two Using Systems .......12
Two Loops with One Adapter ..................14
Two Loops with TwoAdapters ..................15
Large Configurations ......................16
Switching Off Using Systems ..................17
Switching On Using Systems ..................17
Configuring Devices on an SSA Loop ................18
SSA Link Speed .......................18
Identifying and Addressing SSA Devices ...............19
Location Code Format ....................19
Pdisks, Hdisks, and Disk Drive Identification .............19
SSA Unique IDs ......................21
Rules for SSA Loops ......................22
Checking the Level of the Adapter Microcode..............23
Rules for the Physical Relationship between Disk Drives and Adapters .....24
One Pair of Adapter Connectors in the Loop .............24
Pairs of Adapter Connectors in the Loop – Some Shared Data .......25
Pairs Of Adapter Connectors in the Loop – Mainly Shared Data ......26
iii
Reserving Disk Drives .....................27
Fast-Write Cache .......................27
Chapter 3. RAID Functions and Array States .............29
RAID Functions .......................29
Availability ........................29
Disk Drives That Are Not in Arrays ................30
RAID-0 Array States ......................31
Good State ........................31
Offline State........................31
RAID-1 Array States ......................32
RAID-5 Array States ......................33
Good State ........................33
Exposed State .......................33
Degraded State ......................33
Rebuilding State ......................34
Offline State........................34
RAID-5 Array State Flowchart ..................35
RAID-10 Array States .....................36
Good State ........................36
Exposed State .......................36
Degraded State ......................37
Rebuilding State ......................37
Offline State........................37
Unknown State.......................38
Multiple States .......................38
Chapter 4. Using the SSA SMIT Menus ...............39
Getting Access to the SSAAdapters SMIT Menu ............40
Getting Access to the SSA Disks SMIT Menu..............41
Getting Access to the SSA RAID Arrays SMIT Menu ...........43
Chapter 5. Hot Spare Management ................45
Deciding how to Configure Hot Spare Disk Drive Pools ..........45
Choosing How Many Hot Spare Disk Drives to Include in Each Pool ......51
Choosing the Error Threshold (Alarm) Level for a Hot Spare Pool .......51
Rules for Hot Spare Disk Drive Pools ................52
Solving Hot Spare Pool Problems .................53
Chapter 6. Using the RAID Array Configurator ............57
Installing and Configuring SSA RAID Arrays ..............58
Getting Access to the SSA RAID Arrays SMIT Menu ..........59
Adding an SSA RAID Array...................60
Deleting an SSA RAID Array ..................70
Creating a Hot Spare Disk Drive .................72
Changing or Showing the Status of a Hot Spare Pool ..........74
Showing the Disks That Are Protected by Hot Spares ..........77
Listing the Disks That Are in a Hot Spare Pool ............80
Adding a New Hot Spare Pool..................83
Adding Disks to, or Removing Disks from, a Hot Spare Pool........86
iv User’s Guide and Maintenance Information
Dealing with RAID Array Problems .................89
Getting Access to the SSA RAID Array SMIT Menu...........90
Identifying and Correcting or Removing Failed Disk Drives ........91
Installing a Replacement Disk Drive ................95
Using Other Configuration Functions ................97
Getting Access to the SSA RAID Array SMIT Menu...........98
Listing All Defined SSA RAID Arrays ...............100
Listing All Supported SSA RAID Arrays ..............101
Listing All SSA RAID Arrays That Are Connected to a RAID Manager ....102
Listing the Status of All Defined SSA RAID Arrays...........104
Listing or Identifying SSA Physical Disk Drives ............108
Listing or Deleting Old RAID Arrays Recorded in an SSA RAID Manager . . . 130
Changing or Showing the Attributes of an SSA RAID Array ........135
Changing Member Disks in an SSA RAID Array ...........137
Changing or Showing the Use of an SSA Disk Drive ..........144
Changing the Use of Multiple SSA Physical Disks ...........147
||
Copying RAID-1 or RAID-10 Arrays ...............148
|| || | || || | || || || || || || || || | || | || | || || || || || || || || || || || || ||
Chapter 7. Copying Data from Arrays and from Volume Groups ......149
Copying Data from an Array ...................151
Using the ssaraid Command to Create a RAID-Copy Array from a RAID-1 or
RAID-10 Array......................151
Using SMIT to Create a RAID-Copy Array from a RAID-1 or RAID-10 Array 155 Using the ssa_make_copy Command to Create a RAID Copy from a RAID-1 or
RAID-10 Array......................159
ssa_make_copy Command ...................161
Purpose ........................161
Syntax .........................161
Description........................161
Flags .........................162
Example 1: Copying a Complete Volume Group ...........164
Example 2: Copying One Logical Volume .............165
Example 3: Copying One Logical Volume by Logical Volume Name or by FS
Name ........................166
Example 4: Copying One Logical Volume by Logical Volume Name or by FS
Name (2) .......................168
Example 4: Copying a Complete Volume Group and Recreating the Copy on
Another Using System ...................169
Example 5: Running an Automatic Copy of a Volume Group .......170
ssa_delete_copy Command ...................171
Purpose ........................171
Syntax .........................171
Flags .........................171
SMIT Menus for 3-Way Copy Operations...............172
Getting Access to the Array Copy Services Menu ...........172
Array Copy Services ....................173
Effects of Array Copy on Other SMIT Menus .............186
Change/Show Attributes of an SSA RAID Array ...........186
List Status Of All Defined SSA RAID Arrays .............188
Identify Disks in an SSA RAID Array ...............189
Contents v
|| ||
Remove a Disk From an SSA RAID Array .............190
Swap Members of an SSA RAID Array ..............191
Chapter 8. Split-Site Management ................193
Configuration of RAID-1 and RAID-10 Arrays .............193
Operation after a Loss of Member Disks ...............194
One Half of the Array Is Not Present ...............195
Array is Offline because Adapter Is Not Known to the Remaining Half of the
Array .........................203
Array is Offline because the Split and Join Procedure Was Not Performed
Correctly .......................205
Chapter 9. Using the SSA Spare Tool ...............209
Chapter 10. Using the Fast-Write Cache Feature ...........211
Fast-Write Cache Card Battery ..................211
Configuring the Fast-Write Cache Feature ..............211
Getting Access to the Fast-Write Menus ..............213
Enabling or Disabling Fast-Write for One Disk Drive ..........214
Enabling or Disabling Fast-Write for Multiple Devices..........215
Bypassing the Cache in a One-Way Fast-Write Network.........217
Dealing with Fast-Write Problems .................218
SRN 42521 .......................218
SRN 42524 .......................220
SRN 42525 .......................220
Chapter 11. SSA Error Logs ..................221
Error Logging ........................221
Summary ........................221
Detailed Description.....................222
Error Logging Management ...................228
Summary ........................228
Detailed Description.....................228
Error Log Analysis ......................229
Summary ........................229
Detailed Description.....................230
Good Housekeeping .....................233
Chapter 12. Using the SSA Command Line Interface for RAID Configurations 235
Command Syntax ......................237
Options ..........................238
Object Types ........................238
Instruct Types........................238
Examples .........................239
Example 1: To Create a RAID-0 Array...............239
Example 2: To Create a RAID-1 Array...............239
Example 3: To Create a RAID-5 Array...............240
Example 4: To Create a RAID-10 Array ..............240
Example 5: To Create a Hot Spare Pool ..............241
Example 6: To List All Defined SSA Objects .............241
vi User’s Guide and Maintenance Information
Example 7: To Change an Attribute of an Object ...........242
Example 8: To Exchange a Member Disk Drive of an Existing Array .....242
Example 9: To Make a New System Disk..............243
Example 10: To Delete an Array.................243
SSARAID Command Attributes ..................244
RAID Arrays Creation and Change Attributes ............244
RAID Arrays Change Attributes .................248
Hot Spare Pool Creation and Change Attribute ............249
Physical Disk Drive Change Attributes...............249
Action Attributes (RAID-1, RAID-5, and RAID-10 Only) .........251
|| ||
Couple Action Attributes (RAID-1 and RAID-10 Only)..........252
Uncouple Action Attributes (RAID-1 and RAID-10 Only) .........252
Return Codes........................253
Chapter 13. Using the Programming Interface ............255
SSA Subsystem Overview ...................255
Device Drivers ......................255
Interface between the SSA Adapter Device Driver and Head Device Driver 256
Trace Formatting......................256
SSA Adapter Device Driver ...................257
Purpose ........................257
Syntax .........................257
Description........................257
PCI SSAAdapter ODM Attributes ................257
Device-Dependent Subroutines .................258
Summary of SSA Error Conditions ................259
Managing Dumps .....................259
Files ..........................260
IOCINFO (Device Information) SSA Adapter Device Driver ioctl Operation....261
Purpose ........................261
Description........................261
Files ..........................261
SSA_TRANSACTION SSAAdapter Device Driver ioctl Operation.......262
Purpose ........................262
Description........................262
Return Values.......................263
Files ..........................263
SSA_GET_ENTRY_POINT SSA Adapter Device Driver ioctl Operation .....264
Purpose ........................264
Description........................264
Return Values.......................264
Files ..........................264
SSA Adapter Device Driver Direct Call Entry Point............265
Purpose ........................265
Description........................265
Return Values.......................265
ssadisk SSA Disk Device Driver..................266
Purpose ........................266
Syntax .........................266
Configuration Issues ....................266
Contents vii
Device Attributes......................270
Device-Dependent Subroutines .................272
Error Conditions ......................274
Special Files .......................276
IOCINFO (Device Information) SSA Disk Device Driver ioctl Operation .....277
Purpose ........................277
Description........................277
Files ..........................277
SSADISK_ISAL_CMD (ISAL Command) SSA Disk Device Driver ioctl Operation 278
Purpose ........................278
Description........................278
Return Values.......................279
Files ..........................280
SSADISK_ISALMgr_CMD (ISAL Manager Command) SSA Disk Device Driver ioctl
Operation ........................281
Purpose ........................281
Description........................281
Return Values.......................282
Files ..........................282
SSADISK_SCSI_CMD (SCSI Command) SSA Disk Device Driver ioctl Operation 283
Purpose ........................283
Description........................283
Return Values.......................284
Files ..........................284
SSADISK_LIST_PDISKS SSA Disk Device Driver ioctl Operation.......285
Purpose ........................285
Description........................285
Return Values.......................286
Files ..........................286
SSA Disk Concurrent Mode of Operation Interface ...........287
Device Driver Entry Point ...................287
Top Kernel Extension Entry Point ................288
SSA Disk Fencing ......................290
SSA Target Mode ......................291
Configuring the SSA Target Mode ................292
Buffer Management .....................293
Understanding Target-Mode Data Pacing..............293
Using SSA Target Mode ...................294
Execution of Target Mode Requests ...............294
SSA tmssa Device Driver ....................295
Purpose ........................295
Syntax .........................295
Description........................295
Configuration Information ...................296
Device-Dependent Subroutines .................296
Errors .........................302
tmssa Special File ......................304
Purpose ........................304
Description........................304
Implementation Specifics ...................304
viii User’s Guide and Maintenance Information
Related Information .....................304
IOCINFO (Device Information) tmssa Device Driver ioctl Operation ......305
Purpose ........................305
Description........................305
TMIOSTAT (Status) tmssa Device Driver ioctl Operation..........307
Purpose ........................307
Description........................307
TMCHGIMPARM (Change Parameters) tmssa Device Driver ioctl Operation . . . 308
Purpose ........................308
Description........................308
Part 2. Maintenance Information ....................311
Chapter 14. SSA Adapter Information ...............313
Installing the SSA Adapter ...................313
Cron Table Entries ......................313
Microcode Maintenance ....................314
Checking the ID and Level of the Microcode Package .........314
Maintaining the Adapter Microcode................315
Maintaining the Disk Drive Microcode ...............315
Vital Product Data (VPD) for the SSA Adapter .............316
Adapter Power-On Self-Tests (POSTs) ...............317
Chapter 15. Removal and Replacement Procedures ..........319
Exchanging Disk Drives ....................319
Changing Pdisk and Hdisk Numbers ................326
Removing and Replacing an Advanced SerialRAID Adapter ........327
Removing an SDRAM Module of an Advanced SerialRAID Adapter ......329
Installing an SDRAM Module of an Advanced SerialRAID Adapter ......330
Removing the Fast-Write Cache Option Card of an Advanced SerialRAID Adapter 332 Installing the Fast-Write Cache Option Card of an Advanced SerialRAID Adapter 334 Removing the Battery Assembly from the Fast-Write Cache Option Card of an
Advanced SerialRAID Adapter .................336
Installing a Battery Assembly into the Fast-Write Cache Option Card of an
Advanced SerialRAID Adapter .................338
Part Numbers........................340
Chapter 16. Using the SSA Command Line Utilities ..........341
|| || || || || ||
ssa_sesdld Command .....................341
Purpose ........................341
Syntax .........................341
Description........................341
Flags .........................341
Examples ........................342
ssaadap Command ......................343
Purpose ........................343
Syntax .........................343
Description........................343
Flags .........................343
Contents ix
ssacand Command ......................344
Purpose ........................344
Syntax .........................344
Description........................344
Flags .........................344
ssa_certify Command .....................345
Purpose ........................345
Syntax .........................345
Description........................345
Flags .........................345
ssaconn Command ......................347
Purpose ........................347
Syntax .........................347
Description........................347
Flags .........................347
ssa_diag Command......................348
Purpose ........................348
Syntax .........................348
Description........................348
Flags .........................348
Output .........................348
ssadisk Command ......................349
Purpose ........................349
Syntax .........................349
Description........................349
Flags .........................349
ssadload Command......................350
Purpose ........................350
Syntax .........................350
Description........................350
Flags .........................351
Examples ........................351
ssa_ela Command ......................353
Purpose ........................353
Syntax .........................353
Description........................353
Flags .........................353
Output .........................354
ssaencl Command ......................355
Purpose ........................355
Syntax .........................355
Description........................355
Flags .........................355
Examples ........................357
ssa_format Command .....................358
Purpose ........................358
Syntax .........................358
Description........................358
Flags .........................358
Output .........................359
x User’s Guide and Maintenance Information
|| || || || || || ||
ssa_fw_status Command ....................360
Purpose ........................360
Syntax .........................360
Description........................360
Flags .........................360
Output .........................360
Examples ........................360
ssa_getdump Command ....................361
Purpose ........................361
Syntax .........................361
Description........................361
Flags .........................362
Output .........................363
ssaidentify Command .....................364
Purpose ........................364
Syntax .........................364
Description........................364
Flags .........................364
ssa_progress Command ....................365
Purpose ........................365
Syntax .........................365
Description........................365
Flags .........................365
Output .........................365
Examples ........................365
ssa_rescheck Command ....................366
Purpose ........................366
Syntax .........................366
Description........................366
Flags .........................366
Output .........................366
Examples ........................367
Return Codes.......................367
ssa_servicemode Command ...................368
Purpose ........................368
Syntax .........................368
Description........................368
Flags .........................368
Output .........................368
ssa_speed Command .....................369
Purpose ........................369
Syntax .........................369
Description........................369
Flags .........................369
Output .........................370
Examples ........................370
ssavfynn Command......................371
Purpose ........................371
Syntax .........................371
Description........................371
Contents xi
Flags .........................371
Output .........................371
ssaxlate Command ......................372
Purpose ........................372
Syntax .........................372
Description........................372
Flags .........................372
Chapter 17. SSA Service Aids ..................373
The Identify Function .....................375
Starting the SSA Service Aids ..................376
Set Service Mode Service Aid ..................378
Link Verification Service Aid ...................383
Configuration Verification Service Aid ................387
Format Disk Service Aid ....................389
Certify Disk Service Aid ....................391
Display/Download Disk Drive Microcode Service Aid ...........393
Link Speed Service Aid ....................396
Service Aid Service Request Numbers (SRNs) .............400
Using the Service Aids for SSA-Link Problem Determination ........400
Example 1. Normal Loops...................401
Example 2. Broken Loop (Cable Removed) .............403
Example 3. Broken Loop (Disk Drive Removed) ...........406
Finding the Physical Location of a Device ..............409
Finding the Device When Service Aids Are Available ..........409
Finding the Device When No Service Aids Are Available.........409
Chapter 18. SSA Problem Determination Procedures..........411
Service Request Numbers (SRNs) .................411
The SRN Table ......................411
Using the SRN Table ....................411
Software and Microcode Errors ..................441
SSA Loop Configurations that Are Not Valid..............441
SSA Maintenance Analysis Procedures (MAPs) ............443
How to Use the MAPs ....................443
MAP 2010: START ......................444
MAP 2320: SSA Link .....................445
MAP 2323: SSA Intermittent Link Error ...............450
MAP 2324: SSA RAID .....................454
MAP 2410: SSA Repair Verification ................475
SSA Link Errors .......................478
SSA Link Error Problem Determination ..............478
Link Status (Ready) Lights ..................481
Service Aid .......................482
Repair Actions ......................482
Part 3. Appendixes..........................483
Appendix. Communications Statements ..............485
xii User’s Guide and Maintenance Information
Federal Communications Commission (FCC) Statement..........485
Japanese Voluntary Control Council for Interference (VCCI) Statement .....485
Korean Government Ministry of Communication (MOC) Statement ......485
New Zealand Compliance Statement ................485
International Electrotechnical Commission (IEC) Statement.........486
Avis de conformitéàla réglementation d’Industrie Canada .........486
Industry Canada Compliance Statement ...............486
United Kingdom Telecommunications Requirements ...........486
European Union (EU) Statement .................486
Radio Protection for Germany ..................486
Taiwan Class A Compliance Statement ...............487
Glossary .........................489
Index ..........................493
Contents xiii
xiv User’s Guide and Maintenance Information

Safety Notices

For a translation of the danger and caution notices contained in this book, see the Safety Information manual, SA23-2652.

Definitions of Safety Notices

A danger notice indicates the presence of a hazard that has the potential of causing death or serious personal injury.
This book contains no danger notices.
A caution notice indicates the presence of a hazard that has the potential of causing moderate or minor personal injury.
This book contains two caution notices. Those caution notices are in this safety section.
An attention notice indicates an action that could cause damage to a program, device, system, or data.

Safety Notice for Installing, Relocating, or Servicing

Before connecting or removing any cables to or from connectors at the using system, be sure to follow the steps in the installation or relocation checklist specified in the Installation and Service Guide for your using system. For safety checks when servicing, refer to that manual and to the Installation and Service Guide for your subsystem.
CAUTION: A lithium battery can cause fire, explosion, or a severe burn. Do not recharge, disassemble, heat above 100°C (212°F), solder directly to the cell, incinerate, or expose cell contents to water. Keep away from children. Replace only with the part number specified with your system. Use of another battery might present a risk of fire or explosion.
The battery connector is polarized; do not try to reverse the polarity.
Dispose of the battery according to local regulations.
Each Advanced SerialRAID Adapter card contains a lithium battery.
CAUTION: The Fast-Write Cache Option Card contains a nickel-cadmium (NiCad) battery. To avoid possible explosion, do not incinerate the battery. Exchange it only with a manufacturer-approved part. Recycle or discard the battery as instructed by local regulations and where recycling facilities exist.
xv
xvi User’s Guide and Maintenance Information

About This Book

Who Should Use This Book

This book is for people who operate or service a RISC system that contains one or more Advanced SerialRAID Adapters. To follow the instructions in this book, you should be familiar with the basic operational procedures for a RISC system.

What This Book Contains

Part 1 of this book is mainly for the user. It describes:
v The Advanced SerialRAID Adapters v SSA loops v The RAID facilities that are provided by the adapter v How to use the SSA SMIT menus v How to use the RAID configuration utility to configure arrays of SSA disk drives, and
how to deal with problems such as the failure of a disk drive in a RAID array
v How to use the SSA Spare Tool v How to configure the Fast-Write feature v SSA error logs v How to use the SSA Command Line Interface v How to use the programming interface
Part 2 of this book is mainly for service representatives. It describes:
v General technical topics about the Advanced SerialRAID Adapters v Removal and replacement procedures v How to use the SSA Command Line Utilities v The SSA service aids v Problem determination procedures, including Service Request Numbers (SRNs) and
Maintenance analysis procedures (MAPs)
The appendix contains the communications statements for the adapter.
A glossary and an index are provided.

If You Need More Information

The Problem Solving Guide and Reference, SC23-2204, is the first book you should use if you have a problem with your system.
Other books that you might need are:
v The operator guide for your system v Diagnostic Information for Multiple Bus Systems, SA38-0509 v Technical Reference for your adapter
xvii

Web Support Pages

| |
| | |
When you are installing an SSA device or subsystem, upgrading your SSA subsystem, or doing preventive maintenance on your SSA subsystem, refer to the web page shown here. This web page provides access to the latest SSA publications, micorocde, and support information for the using system, SSA adapters, and SSA subsystem.
|
http://www.storage.ibm.com/hardsoft/products/ssa
|

Numbering Convention

In this book:
KB means 1 000 bytes. MB means 1 000 000 bytes. GB means 1 000 000 000 bytes.
xviii User’s Guide and Maintenance Information

Part 1. User Information

1
2 User’s Guide and Maintenance Information

Chapter 1. Introducing SSA and the Advanced SerialRAID Adapters

This chapter describes:
v Serial storage architecture (SSA). v The Advanced SerialRAID Adapter and the Advanced SerialRAID Plus Adapter.
Physically, the two types of adapter are the same. The Advanced SerialRAID Plus Adapter, however, provides additional functions.
In this book, the name “Advanced SerialRAID Adapter” is used both for the Advanced SerialRAID Adapter and for the Advanced SerialRAID Plus Adapter, unless otherwise stated.

Serial Storage Architecture (SSA)

Serial Storage Architecture (SSA) is an industry-standard interface that provides high-performance fault-tolerant attachment of I/O storage devices. In SSA subsystems, transmissions to several destinations are multiplexed; the effective bandwidth is further increased by spatial reuse of the individual links. Commands are forwarded automatically from device to device along a loop until the target device is reached. Multiple commands can be travelling around the loop simultaneously. SSA retains the SCSI-2 commands, queuing model, and status and sense bytes.
3

The Advanced SerialRAID Adapters (type 4–P)

The Advanced SerialRAID Adapters (see Figure 1) are 40-MB-per-second Serial Storage Architecture (SSA), Peripheral Component Interconnect (PCI) adapters that serve as the interface between systems that use PCI architecture and devices that use SSA. These adapters provide support for two SSA loops. Each loop can contain a maximum of eight pairs of adapter connectors and a maximum of 48 disk drives. See also “Rules for SSA Loops” on page 22.
1 Connector B2 5 Green light 2 Green light 6 Connector A1 3 Connector B1 7 Type-number label 4 Connector A2
1 2 3
4 5 6
7
Figure 1. An Advanced SerialRAID Adapter Card (Type 4–P)
4 User’s Guide and Maintenance Information
4-P
Note: In the SSA service aids, this adapter is called “IBM SSA 160 SerialRAID Adapter
(14109100)”.
The adapter card has four SSA connectors that are arranged in two pairs. Connectors A1 and A2 are one pair; connectors B1 and B2 are the other pair.
The SSA links must be configured as loops. Each loop is connected to a pair of connectors at the SSA adapter card. These connectors must be a valid pair (that is, A1 and A2 or B1 and B2); otherwise, the disk drives on the loop are not fully configured, and the diagnostics fail. Operations to all the disk drives on a particular loop can continue if that loop breaks at any one point.
This adapter also contains array management software that provides RAID functions to control the arrays of the RAID subsystem (see also Chapter 3, “RAID Functions and Array States” on page 29). An array can contain several member disk drives. Each array is handled as one disk by the operating system. The array management software translates requests to this disk into requests to the member disk drives. Although this adapter is a RAID adapter, it can be configured so that all, some, or none of the disk drives that are attached to it are member disk drives of arrays.
The Advanced SerialRAID Adapter can be connected, by way of one or two SSA loops, to other SSA adapters. These adapters can be either in the same using system, or in separate using systems. (See “Rules for SSA Loops” on page 22 for details of valid configurations.)

Fast-Write Cache Feature

An optional 32 MB Fast-Write Cache feature is available for the Advanced SerialRAID Adapter. This feature improves performance for jobs that include many write operations.

128 MB Memory Module Feature

An optional 128 MB dual inline memory module (DIMM) feature is available. This feature is recommended for two-way fast-write operations.
Chapter 1. Introducing SSA and the Advanced SerialRAID Adapters 5

Lights of the Advanced SerialRAID Adapters

Each pair of connectors has a green light that indicates the operational status of its related loop:
Status of Light Meaning Off Both SSA connectors are inactive. If disk drives or other SSA
adapters are connected to these connectors, either those disk drives or adapters are failing, or their SSA links are not active.
Permanently on
Both SSA links are active (normal operating condition).
Slow Flash Only one SSA link is active.

Port Addresses of the Advanced SerialRAID Adapters

The port addresses used in some SRNs that relate to these adapters can be numbers 0 through 3. They correspond to the port connectors on the SSA adapter:
0 = Connector A1 1 = Connector A2 2 = Connector B1 3 = Connector B2

SSA Adapter ID during Bring-Up

All adapters that can be used on RISC using systems generate a three-digit configuration program indicator number. During system bring-up, this indicator number appears on the three-digit display of the using system. The numbers are:
80C Advanced SerialRAID Adapter (type 4-P) is being identified or configured.
6 User’s Guide and Maintenance Information

Chapter 2. Introducing SSA Loops

This chapter describes the principles of SSA loops, how SSA devices are known to the system programs, and the rules that you must observe when you configure your SSA loops.

Loops, Links, and Data Paths

In the simplest SSA configuration, SSA devices are connected through two or more SSA links to an SSA adapter that is located in a using system. The devices, SSA links, and SSA adapter are configured in loops. Each loop provides a data path that starts at one connector of the SSA adapter and passes through a link (SSA cable) to the devices. The loop continues through the devices, then returns through another link to a second connector on the SSA adapter.
The maximum permitted length for an external copper cable that connects two SSA nodes (for example, disk drives) is 25 meters (82 feet).
The maximum permitted length for an external fiber optic cable that connects two SSA nodes (for example, disk drives) is 10 kilometers (32800 feet). Some devices, however, can operate only at shorter distances. See your subsystem documentation for details.
Details of the rules for configuring SSA loops are given for each SSA adapter in “Rules for SSA Loops” on page 22.
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Simple Loop

Figure 2 shows a simple SSA loop. The devices that are attached to the SSA adapter card 1 are connected through SSA links 2. These SSA links are configured as a loop. Data and commands to a particular device pass through all other devices on the link between the adapter and the target device.
Data can travel in either direction round the loop. The adapter can, therefore, get access to the devices 3 (disk drives in this example) through two data paths. The adapter always, however, uses the path that has the fewest interconnecting devices between the adapter and the destination device. The using system cannot detect which data path is being used.
Using system
A1 A2 B1 B2
Disk1Disk2Disk3Disk4Disk5Disk6Disk7Disk
Figure 2. Simple Loop
8 User’s Guide and Maintenance Information
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Simple Loop — One Disk Drive Missing

If a disk drive fails, or is switched off, the loop is broken, and one of the data paths to a particular disk drive is no longer available. The disk drives on the remainder of the loop continue to work, but an error is reported to the system. The adapter now uses the alternative path to some of the devices.
In Figure 3, disk drive number 3 has failed. Disk drives 1 and 2 can communicate with the using system only through connector A1 of the SSA adapter. Disk drives 4 through 8 can communicate only through connector A2 of the SSA adapter.
A1 A2 B1 B2
Using system
Disk1Disk2Disk3Disk4Disk5Disk6Disk7Disk
Figure 3. Simple Loop with One Disk Drive Missing
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Chapter 2. Introducing SSA Loops 9

Simple Loop — Two Disk Drives Missing

If two or more disk drives are switched off, fail, or are removed from the loop, some disk drives might become isolated from the SSA adapter.
In Figure 4, disk drives 3 and 7 have been removed. Disk drives 1 and 2 can communicate with the using system only through connector A1 of the SSA adapter. Disk drive number 8 can communicate with the using system only through connector A2 of the SSA adapter. Disk drives 4, 5, and 6 are isolated from the SSA adapter.
Using system
A1 A2 B1 B2
Disk1Disk2Disk3Disk4Disk5Disk6Disk7Disk
Figure 4. Simple Loop with Two Disk Drives Missing
10 User’s Guide and Maintenance Information
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