First Edition (December 1998)
Part Number EK-HSZ80-RG. A01/388222-001
Compaq Computer Corporation
While Compaq Computer Corporation believes the information included in this manual is correct as of the date
of publication, it is subject to change without notice. Compaq makes no representations that the interconnec-
tion of its products in the manner described in this document will not infringe existing or future patent rights,
nor do the descriptions contained in this document imply the granting of licenses to make, use, or sell equip-
ment or software in accordance with the description. No responsibility is assumed for the use or reliability of
firmware on equipment not supplied by Compaq or its affiliated companies. Possession, use, or copying of the
software or firmware described in this documentation is authorized only pursuant to a valid written license
from Compaq, an authorized sublicensor, or the identified licensor.
Commercial Computer Software, Computer Software Documentation and Technical Data for Commercial
Items are licensed to the U.S. Government with Compaq's standard commercial license and, when applicable,
the rights in DFAR 252.227 7015, "Technical Data-Commercial Items."
1998 Compaq Computer Corporation.
All rights reserved. Printed in U.S.A.
Compaq, the Compaq logo, DIGITAL, DIGITAL UNIX, DECconnect, HSZ, HSG, StorageWorks, VMS,
OpenVMS Registered in the United States Patent and Trademark Office.
UNIX is a registered trademark in the United States and other countries exclusively through X/Open Company
Ltd. Windows NT is a registered trademark of the Microsoft Corporation. Sun is a registered trademark of Sun
Microsystems, Inc. Hewlett-Packard, TACHYON, and HP-UX are registered trademarks of the Hewlett-Pack-
ard Company. IBM and AIX are registered trademarks of International Business Machines Corporation. All
other trademarks and registered trademarks are the property of their respective owners.
This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to
Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interfer-
ence when the equipment is operated in a commercial environment. This equipment generates, uses and can
radiate radio frequency energy and, if not installed and used in accordance with the manuals, may cause harm-
ful interference to radio communications. Operation of this equipment in a residential area is likely to cause
harmful interference in which case the user will be required to correct the interference at his own expense.
Restrictions apply to the use of the local-connection port on this series of controllers; failure to observe these
restrictions may result in harmful interference. Always disconnect this port as soon as possible after complet-
ing the setup operation. Any changes or modifications made to this equipment may void the user's authority to
operate the equipment.
Warning!
This is a Class A product. In a domestic environment this product may cause radio interference in which case
the user may be required to take adequate measures.
Achtung!
Dieses ist ein Gert der Funkstrgrenzwertklasse A. In Wohnbereichen knnen bei Betrieb dieses Gertes
Rundfunkstrungen auftreten, in welchen Fllen der Benutzer fr entsprechende Gegenmanahmen verant-
wortlich ist.
Attention!
Ceci est un produit de Classe A. Dans un environnement domestique, ce produit risque de crer des inter-
frences radiolectriques, il appartiendra alors l'utilisateur de prendre les mesures spcifiques appropries.
JAPAN
USA
This equipment generates, uses, and may emit radio frequency energy. The equipment has been type tested and
found to comply with the limits for a Class A digital device pursuant to Part 15 of FCC rules, which are
designed to provide reasonable protection against such radio frequency interference. Operation of this equip-
ment in a residential area may cause interference in which case the user at his own expense will be required to
take whatever measures may be required to correct the interference. Any modifications to this device - unless
expressly approved by the manufacturer - can void the user's authority to operate this equipment under part 15
of the FCC rules.
v
About This Guide
Getting Help. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvi
Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xviii
Required Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xx
Related Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxi
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxii
Cha p ter 1
General Description
Typical Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Summary of HSZ80 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
The HSZ80 Array Controller. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Cache Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
External Cache Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Cha p ter 2
Configuring an HSZ80 Array Controller
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Configuring an HSZ80 Array Controller. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Setting the PVA Module ID Switch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
Establishing a Local Connection to the Controller . . . . . . . . . . . . . . . . . . . . . . . . 226
Selecting a Failover Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
Enabling Mirrored Write-Back Cache. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
Setting SCSI Target ID Numbers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
Using Preferred ID Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
vi
Chapter 3
Creating Storagesets
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Planning and Configuring Storagesets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Creating a Storageset and Device Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Determining Storage Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Choosing a Storageset Type. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Cloning Data for Backup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320
Backing Up Your Subsystem Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325
Node IDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330
Assigning Unit Numbers for Host Access to Storagesets . . . . . . . . . . . . . . . . . . . 332
Creating a Storageset Map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334
Planning Partitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340
Choosing Switches for Storagesets and Devices . . . . . . . . . . . . . . . . . . . . . . . . . . 342
RAIDset Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343
Mirrorset Switches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345
Device Switches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 348
Initialize Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351
Unit Switches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 358
Cha p ter 4
Configuring Storagesets
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Configuring with the Command Console LUN. . . . . . . . . . . . . . . . . . . . . . . . . . . 419
Configuring Units with Multiple Hosts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423
Moving Storagesets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 435
vii
Cha p ter 5
CLI Commands
CLI Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
ADD DISK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
ADD MIRRORSET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 511
ADD PASSTHROUGH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 516
ADD RAIDSET. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 519
ADD SPARESET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 523
ADD STRIPESET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 524
ADD UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 527
CLEAR_ERRORS CLI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 535
CLEAR_ERRORS controller INVALID_CACHE . . . . . . . . . . . . . . . . . . . . . . . . 536
CLEAR_ERRORS device-name UNKNOWN . . . . . . . . . . . . . . . . . . . . . . . . . . . 538
CLEAR_ERRORS unit-number LOST_DATA. . . . . . . . . . . . . . . . . . . . . . . . . . . 540
CLEAR_ERRORS unit-number UNWRITEABLE_DATA . . . . . . . . . . . . . . . . . 542
CONFIGURATION RESET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 544
CONFIGURATION RESTORE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 545
CONFIGURATION SAVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 547
CREATE_PARTITION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 548
DELETE container-name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 551
DELETE FAILEDSET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 553
DELETE SPARESET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 554
DELETE unit-number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 555
DESTROY_PARTITION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 557
DIRECTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 559
HELP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 560
INITIALIZE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 562
LOCATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 567
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
viii
MIRROR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 570
POWEROFF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 574
REDUCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 577
RENAME. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 581
RESTART controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 583
RETRY_ERRORS unit-number UNWRITEABLE_DATA . . . . . . . . . . . . . . . . . 585
RUN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 586
SELFTEST controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 589
SET controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 591
SET device-name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5102
SET EMU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5105
SET FAILEDSET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5108
SET FAILOVER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5110
SET mirrorset-name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5112
SET MULTIBUS_FAILOVER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5118
SET NOFAILOVER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5120
SET NOMULTIBUS_FAILOVER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5122
SET RAIDset-name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5124
SET unit-number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5128
SHOW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5136
SHUTDOWN controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5143
UNMIRROR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5145
ix
A ppendix A
System Profiles
Device Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A2
Storageset Profile. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A3
Enclosure Template . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A4
A ppendix B
Controller Specifications
Physical and Electrical Specifications for the Controller . . . . . . . . . . . . . . . . . . . B2
Environmental Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B3
Glossary
Index
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
xi
Figures
Basic Building Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Bridging the Gap Between the Host and Its Storage Subsystem . . . . . . . . . . . . . . 17
HSZ80 Array Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Parts Used in Configuring the HSZ80 Array Controller . . . . . . . . . . . . . . . . . . . 110
Optional Maintenance Port Cable for a Terminal Connection . . . . . . . . . . . . . . . 112
Location of Controllers and Cache Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
HSZ80 Controller Operator Control Panel (OCP) . . . . . . . . . . . . . . . . . . . . . . . . 114
Cache Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
ECB for Dual-Redundant Controller Configurations . . . . . . . . . . . . . . . . . . . . . . 130
Cabling for a Single-Controller Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Cabling for a Dual-Redundant Controller Configuration in
Transparent Failover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
Cabling for a Dual-Redundant Controller Configuration in
Multiple-Bus Failover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
SCSI Target ID Numbers on the Controller Device Bus and PVA Settings in
an Extended Subsystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
PC/Terminal to Maintenance Port Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
"This Controller" and "Other Controller" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
Host SCSI Bus and Controller Device Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
Units Created from Storagesets, Partitions, and Drives . . . . . . . . . . . . . . . . . . . . . 33
Storageset Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Striping Lets Several Disk Drives Participate in Each I/O Request . . . . . . . . . . . . 39
Distribute Members across Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311
Mirrorsets Maintain Two Copies of the Same Data . . . . . . . . . . . . . . . . . . . . . . . 313
First Mirrorset Members on Different Buses . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
Parity Ensures Availability; Striping Provides Good Read Performance . . . . . . . 316
Striping and Mirroring in the Same Storageset . . . . . . . . . . . . . . . . . . . . . . . . . . 318
CLONE Steps for Duplicating Unit Members . . . . . . . . . . . . . . . . . . . . . . . . . . . 321
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
xii
Storageset Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335
PTL Naming Convention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337
PTL Addressing in an Extended Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . 338
Locating Devices using PTLs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339
Partitioning a Single-Disk Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340
Chunk Size Larger than the Request Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 352
Chunk Size Smaller than the Request Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353
Setting Host Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 425
Accessing Units on a Given Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 427
Accessing Units with the Host Port's SCSI ID Number . . . . . . . . . . . . . . . . . . . . 429
Accessing Units through Port Access and the Host Port's SCSI ID Number . . . 431
Assigning Units through Multiple Host Adapters . . . . . . . . . . . . . . . . . . . . . . . . 433
Moving a Storageset from one Subsystem to Another . . . . . . . . . . . . . . . . . . . . . 435
xiii
Tables
Basic Building Blocks List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Summary of Controller Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
HSZ80 Array Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Description of Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Parts of the Optional Maintenance Port Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
Cache Module Memory Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Location of Cache Module Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Cache Policies and Cache Module Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Resulting Cache Policies and ECB Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
ECB Capacity Based on Memory Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Location of Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Location of Parts for a Single Controller Configuration . . . . . . . . . . . . . . . . . . . 25
Location of Parts for Transparent Failover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
Location of Parts for Multiple-Bus Failover . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
Controller Limitations for RAIDsets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
A Comparison of Different Kinds of Storagesets . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Unit Numbering Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333
Maximum Chunk Sizes for a RAIDset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354
UNIT Switches for Storagesets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 358
Recall and Edit Command Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Unit Numbering Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
ADD UNIT Switches for Storagesets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 528
Poweroff Switch Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 575
SET controller Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 591
Maximum SCSI-Bus Lengths for Given Data Transfer Rate . . . . . . . . . . . . . . . 5100
EMU Set Point Temperatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5106
SET UNIT Switches for Existing Containers . . . . . . . . . . . . . . . . . . . . . . . . . . . 5129
Controller Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B2
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
xiv
Optimum Operating Environmental Specifications . . . . . . . . . . . . . . . . . . . . . . . .B3
Maximum Operating Environmental Specifications . . . . . . . . . . . . . . . . . . . . . . . B4
Maximum Nonoperating Environmental Specifications . . . . . . . . . . . . . . . . . . . . B4
xv
About This Guide
This book describes the features of the HSZ80 Array Controller, configuration
procedures for the controller and storagesets running Array Controller Software
(ACS) 8.3Z, and the CLI commands used in configuring.
This book does not contain information about the operating environments to which
the controller may be connected, nor does it contain detailed information about
subsystem enclosures or their components. See the documentation that accompanied
those peripherals for information about them.
Getting Help
If you have a problem and have exhausted the information in this reference guide, you
can get further information and other help in the following locations.
Compaq Website
The Compaq Website has information on this product as well as the latest drivers and
Flash ROM images. You can access the Compaq website by logging on to the Internet
at http://www.compaq.com.
Telephone Numbers
For Compaq technical support:
In the United States and Canada, call 1-800-652-6672.
For Compaq technical support phone numbers outside the United States and Canada,
visit the Compaq Website at: http://www.compaq.com.
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
xvi About This Guide
Precautions
Follow these precautions when you're carrying out the procedures in this book.
Electrostatic Discharge Precautions
Static electricity collects on all nonconducting material, such as paper, cloth, and
plastic. An electrostatic discharge (ESD) can easily damage a controller or other
subsystem component even though you may not see or feel the discharge. Follow
these precautions whenever you're servicing a subsystem or one of its components:
s Always use an ESD wrist strap when servicing the controller or other
components in the subsystem. Make sure that the strap contacts bare skin and fits
snugly, and that its grounding lead is attached to a bus that is a verified earth
ground.
s Before touching any circuit board or component, always touch a verifiable earth
ground to discharge any static electricity that may be present in your clothing.
s Always keep circuit boards and components away from nonconducting material.
s Always keep clothing away from circuit boards and components.
s Always use antistatic bags and grounding mats for storing circuit boards or
components during replacement procedures.
s Always keep the ESD cover over the program card when the card is in the
controller. If you remove the card, put it in its original carrying case. Never touch
the contacts or twist or bend the card while you're handling it.
s Do not touch the connector pins of a cable when it is attached to a component or
host.
Component Precaution
System components referenced in this manual comply to regulatory standards
documented herein. Use of other components in their place may violate country
standards, negate regulatory compliance, or invalidate the warranty on your product.
xvii
VHDCI Cable Precautions
All of the cables to the controller, cache module, and external cache battery use very-
high-density cable interconnect connectors (VHDCI). These connectors have
extraordinarily small mating surfaces that can be adversely affected by dust and
movement.
Use the following precautions when you're connecting cables that use VHDCI
connectors:
s Clean the mating surfaces with a blast of clean air.
s Mate the connectors by hand, then tighten the retaining screws to 1.5 inch-
pounds--approximately 1/4 additional turn after the connectors have fully mated.
s Test the assembly by gently pulling on the cable, which should not produce
visible separation.
Maintenance Port Precautions
The maintenance port generates, uses, and radiates radio-frequency energy through
cables that are connected to it. This energy may interfere with radio and television
reception. Do not leave a cable connected to this port when you're not communicating
with the controller.
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
xviii About This Guide
Conventions
This book uses the following typographical conventions and special notices to help
you find what you're looking for.
Typographical Conventions
Convention Meaning
ALLCAPS Command syntax that must be entered exactly as shown
and for commands discussed within text, for example:
SET FAILOVER COPY=OTHER_CONTROLLER
"Use the SHOW SPARESET command to show the contents of
the spareset."
Screen display.
Monospaced
Sans serif italic Command variable or numeric value that you supply, for
example:
SHOW RAIDset-name or
set this_controller id=(n,n,n,n,)
Reference to other books, for example: "See .... for
italic
details."
. Indicates that a portion of an example or figure has been
. omitted.
"this controller" The controller serving your current CLI session through a
local or remote terminal.
"other controller" The controller in a dual-redundant pair that's connected
to the controller serving your current CLI session.
xix
Special Notices
This book doesn't contain detailed descriptions of standard safety procedures.
However, it does contain warnings for procedures that could cause personal injury and
cautions for procedures that could damage the controller or its related components.
Look for these symbols when you're carrying out the procedures in this book:
WARNING: A warning indicates the presence of a hazard that can cause
personal injury if you do not observe the precautions in the text.
CAUTION: A caution indicates the presence of a hazard that might dam-
age hardware, corrupt software, or cause a loss of data.
IMPORTANT: An important note is a type of note that provides information
essential to the completion of a task. Users can disregard information in a note
and still complete a task, but they should not disregard an important note.
NOTE: A note provides additional information that's related to the completion of an
instruction or procedure.
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
xx About This Guide
Required Tools
You'll need the following tools to service the controller, cache module, external cache
battery (ECB), the Power Verification and Addressing (PVA) module and the I/O
module:
s A flathead screwdriver for loosening and tightening the I/O module retaining
screws.
s A small phillips screwdriver for loosening and tightening the GLM access door
screws.
s An antistatic wrist strap.
s An antistatic mat on which to place modules during servicing.
s A Storage Building Block (SBB) Extractor for removing StorageWorks building
blocks. This tool is not required, but it will enable you to perform more
efficiently.
xxi
Related Publications
The following table lists some of the Compaq StorageWorks documents related to the
use of the controller, cache module, external cache battery, graphical user interface,
and the subsystem.
Document Title Part Number
BA370 Enclosure Rack Template (Compaq 42U Rack) 355224-001 EK-RKTMP-TP
Command Console Version 2.1 HSZ80 User's Guide 388725-001 AA-RF9TA-TE
Disaster Tolerant Solutions Getting Started Guide for N/A AA-RC3CA-TE
DIGITAL UNIX
Disaster Tolerant Solutions User's Guide for DIGITAL N/A EK-SWXDT-OP
UNIX
External Cache Battery Shelf Installation Card 355222-001 EK-HSECB-IC
(Compaq 42U Rack)
Hardware Configuration Poster for HSZ80 388724-001 EK-HSZ80-CP
HSZ80 Array Controller ACS V8.3 for DIGITAL UNIX N/A AG-RFA0A-BE
CD-ROM
HSZ80 Array Controller ACS V8.3 for DIGITIAL UNIX 388713-001 AA-RF9YA-TE
Release Notes
HSZ80 Array Controller ACS V8.3 for IBM-AIX Release 388711-001 AA-RFALA-TE
Notes
HSZ80 Array Controller ACS V8.3 for OpenVMS Release 388712-001 AA-RFAEA-TE
Notes
HSZ80 Array Controller ACS V8.3 Maintenance and 388221-001 EK-HSZ80-SV
Service Guide
HSZ80 Array Controller Illustrated Parts Map 388220-001 EK-HSZ80-MP
Installation Card (Compaq 42U Rack) 355210-001 EK-H80RM-IC
Installing a Ferrite Bead on a Host Bus N/A EK-SWXES-IG
The RAIDBOOK--A Source for RAID Technology N/A RAID Advisory Board
RA8000/ESA12000 HSZ80 ACS V8.3 for DIGITAL UNIX 388701-001 AA-RF9ZA-TE
Installation Reference Manual
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
xxii About This Guide
Document Title Part Number
RA8000/ESA12000 HSZ80 ACS V8.3 for DIGITAL UNIX 388700-001 AA-RF9XA-TE
Quick Setup Guide
RA8000/ESA12000 HSZ80 ACS V8.3 for IBM-AIX 388710-001 AA-RFAMA-TE
Installation Reference Manual
RA8000/ESA12000 HSZ80 ACS V8.3 for IBM-AIX Quick 388709-001 AA-RFAKA-TE
Setup Guide
RA8000/ESA12000 HSZ80 ACS V8.3 for OpenVMS 388733-001 AA-RFAFA-TE
Installation Reference Manual
RA8000/ESA12000 HSZ80 ACS V8.3 for OpenVMS Quick 388732-001 AA-RFADA-TE
Setup Guide
RA8000/ESA12000 Storage Subsystem User's Guide 387404-001 EK-SMCPR-UG
Rail Mounting Installation Card (Compaq 42U Rack) 355223-001 EK-H8RMB-IC
Ultra SCSI RAID Enclosure (DS-BA370 Series) User's 387403-001 EK-BA370-UG
Guide
Warranty Terms and Conditions N/A EK-HSXSW-WC
Revision History
This is a new document.
11
Chapter 1
General Description
This chapter illustrates and describes in general terms your subsystem and its major
components: the HSZ80 Array Controller, its cache module, and its external cache
battery (ECB).
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
12 General Description
Typical Installation
Figure shows the major components, or basic building blocks, of the storage
subsystem that is comprised of the following:
s One BA370 rack-mountable enclosure.
s Two controllers, each supported by a cache module.
s Two External Cache Batteries (ECBs) in one Storage Building Block (SBB),
which provide backup power to the cache modules during a primary power
failure.
s One environmental monitoring unit (EMU) that monitors the subsystem's
environment and alerts the controller of equipment failures that could cause an
abnormal environment.
s One Power Verification and Addressing (PVA) module that provides a unique
address to each enclosure in an extended subsystem.
s Six I/O modules that integrate the SBB shelf with either an 8-bit single-ended,
16-bit single-ended, or 16-bit differential SCSI bus
s Two cache modules, which support nonvolatile memory and dynamic cache
policies to protect the availability of its unwritten (write-back) data
13
1
16
2
15
13 14
3
12 2x
4
11
10
9 2x
5
8 2x
6
7
CXO6742A
Figure 11. Basic Building Block
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
14 General Description
Table 11 Basic Building Blocks List
Item Description
1 BA370 rack-mountable enclosure
2 Cooling fan
3 Power cable kit
4 I/O module
5 SCSI hub, 3 port
6 SCSI hub, 5 port
7 SCSI hub, 9 port, upgrade
8 Cache module
9 HSZ80 controller
10 PVA module
11 EMU
12 AC input module
13 180-watt power supply
14 Disk drive, 4 GB, 7200
Disk drive, 9 GB, 7200
Disk drive, 18 GB, 7200
Disk drive, 9 GB, 10K
Disk drive, 18 GB, 10K
15 Power cable
16 ECB, dual (shown)
ECB, single (not shown)
15
Summary of HSZ80 Features
Table 12 summarizes the features of the controller:
Table 12 Summary of Controller Features
Feature Supported
Topology Dual host port Ultra SCSI
Host protocol SCSI-2, Limited SCSI-3
Host bus interconnect Wide Ultra SCSI, Differential
Number of host ports 2 on Wide Ultra SCSI, Differential
Device protocol SCSI-2
Device bus interconnect Wide Ultra SCSI, Single-ended
Number of SCSI device ports (or I/O modules) 6 Wide Ultra SCSI, Single-ended
Number of SCSI device targets per port 12
Maximum number of SCSI target devices 72 Ultra SCSI disks
RAID levels supported 0, 1, 0+1, 3/5
Cache module memory sizes supported 64 MB, 128 MB, 256 MB, 512 MB
Maximum cache module size 512 MB
PCMCIA program card software upgrades Yes
Device warm swap Yes
Exercisers available for testing disks Yes
Maximum number of RAID-5 storagesets 20
Maximum number of RAID-5 and RAID-1 storagesets 30
Maximum number of RAID-5, RAID-1, and RAID-0 45
storagesets
Maximum number of units presented to the host 128
Maximum number of partitions per storageset 8
Maximum members per mirrorset 6
Maximum number of members per RAID-5 storageset 14
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
16 General Description
Table 12 Summary of Controller Features (Continued)
Feature Supported
Maximum number of members in a stripeset 24
Maximum number of physical devices in a striped 48
mirrorset
Maximum host port transfer speed 20 MHz
Largest device, storageset, or unit size 512 GB
17
The HSZ80 Array Controller
Your controller is the intelligent bridge between your host and the devices in your
subsystem.
Storage
Host
subsystem
Controller
CXO5505A
Figure 12. Bridging the Gap Between the Host and Its Storage Subsystem
The controller shown in Figure 12 is an integral part of any storage subsystem
because it provides a host with high-performance and high-availability access to
storage devices. See the HSZ80 Array Controller ACS Version 8.3 Release Notes for
the most recent list of supported devices and operating systems.
The controller provides the ability to combine several ordinary disk drives into a
single, high-performance storage unit called a storageset. Storagesets are
implementations of RAID technology, which ensures that every unpartitioned
storageset, whether it uses two disk drives or ten, looks like a single storage unit to the
host. See Chapter 3 and Chapter 4 for more information about storagesets and how to
configure them.
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
18 General Description
From the host's perspective, the controller is simply another device connected to one
of its I/O buses. Consequently, the host sends its I/O requests to the controller just as
it would to any SCSI device. From the subsystem's perspective, the controller
receives the I/O requests and directs them to the devices in the subsystem. Because
the controller processes the I/O requests, the host isn't burdened by the processing
that's typically associated with reading and writing data to multiple storage devices.
Figure 13 shows an HSZ80 Array Controller. Figure 14 shows the parts used in
configuring it and Table 14 lists the descriptions and part numbers.
NOTE: The maintenance port cable shipped with the controller has a 9-pin
connector for a PC connection only. If you are using a terminal instead of a PC or if
you have a system with a DB25 connection, you can obtain a cable as shown in
Figure 15 on page 112 from the local field service office.
To determine which parts you need for your configuration, you must have an idea of
the type of configuration you will be running in your subsystem. See the following
sections for your configuration type:
s "Configuring a Single Controller," page 25
s "Configuring Dual-Redundant Controllers in Transparent Failover Mode,"
page 210
s "Configuring Dual-Redundant Controllers in Multiple-Bus Failover Mode,"
page 216
The components that you'll use most often are conveniently located on the
controller's front panel, such as the maintenance port and the operator control panel
(OCP). The host port and program-card slot are also located on the front panel,
making it easy to update the controller's software or to connect the controller to a
different host.
19
1 2
3
4 5
6
6
5
4
3
2
1
7
8
CXO6284B
Figure 13. HSZ80 Array Controller
Table 13 HSZ80 Array Controller
Item Description
Backplane connector
Host port 1
Host port 2
Program card slot
Program card ejection button
Release lever
Maintenance port
Operator Control panel
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
110 General Description
2
1
3
4
6
5
4
3
2
1
5
6
7
10
8
9
CXO6492B
Figure 14. Parts Used in Configuring the HSZ80 Array Controller
Table 14 Description of Parts
Item Description
Host port 1
Host port 2
ESD/PCMCIA program card
ESD/PCMCIA program card cover
Trilink connectors
Host bus cable
111
Table 14 Description of Parts (Continued)
Item Description
Ferrite bead
Terminator
Jumper cable
Maintenance port cable
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
112 General Description
1
2
3
4
5
CXO6505B
Figure 15. Optional Maintenance Port Cable for a Terminal Connection
Table 15 Parts of the Optional Maintenance Port Cable
Item Description
Cable assembly
Ferrite bead
RJ-11 Adapter
RJ-11 Extension Cable
PC Serial Port Adapter
Each controller is supported by its own cache module. Figure 16 shows which cache
module supports which controller in a dual-redundant controller configuration in a
BA370 rack-mountable enclosure.
113
EMU PVA
Controller A
Controller B
Cache module A Cache module B
CXO6283A
Figure 16. Location of Controllers and Cache Modules
IMPORTANT: Compaq recommends that you use the slots for controller A and
cache module A for single controller configurations. Slot A responds to SCSI tar-
get ID number 7 on the device buses and slot B responds to SCSI target ID num-
ber 6 on the device buses.
Operator Control Panel
The operator control panel (OCP) contains a reset button and six port button LEDs as
shown in Figure 17. The reset button flashes about once per second to indicate that
the controller is operating normally. The port button LEDs correspond to the
controller's device ports and remain off during normal operation. If an error occurs,
the reset button and LEDs will illuminate in a solid or flashing pattern to help you
diagnose the problem.
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
114 General Description
Reset button/ Port button/
LED LED
1 2 3 4 5 6
CXO6216A
Figure 17. HSZ80 Controller Operator Control Panel (OCP)
See Figure 13 on page 19 for the location of the OCP on the HSZ80 Array
Controller.
Under normal circumstances, you will not need to remove the controller from its
enclosure. For this reason, the components that you will use most often are
conveniently located on the front panel. For example, the maintenance port provides a
convenient way to connect a PC or terminal to your controller so that you can interact
with it.
After you configure your controller, you should periodically check its control panel. If
an error occurs, one or more of the LEDs on the control panel will flash in a pattern
that will help you to diagnose the problem. See the HSZ80 Array Controller ACS
Version 8.3 Maintenance and Service Guide for details about troubleshooting your
controller.
Maintenance Port
You can access the controller in two ways: through a PC or terminal via the
maintenance port or through a remote terminal--sometimes called a virtual terminal
or host console--via the host. Compaq recommends that you use a PC or terminal to
carry out the troubleshooting and servicing procedures in this manual. See
"Establishing a Local Connection to the Controller," page 226, for more information
about connecting the controller with a maintenance port cable.
115
Utilities and Exercisers
The controller's software includes the following utilities and exercisers to assist in
troubleshooting and maintaining the controller and the other modules that support its
operation. For more details on each of the utilities and exercisers, see the HSZ80
Array Controller ACS Version 8.3 Maintenance and Service Guide.
Fault Management Utility
The Fault Management Utility (FMU) provides a limited interface to the controller's
fault management system. As a troubleshooting tool, you can use FMU to:
s Display the last-failure and memory-system-failure entries that the fault
management software stores in the controller's nonvolatile memory.
s Translate many of the event messages that are contained in the entries related to
the significant events and failures. For example, entries may contain codes that
indicate the cause of the event, the software component that reported the event,
the repair action, and so on.
s Set the display characteristics of spontaneous events and failures that the fault
management system sends to the PC or terminal, or to the host.
Virtual Terminal Display
Use the virtual terminal display (VTDPY) utility to aid in troubleshooting the
following issues:
s Communication between the controller and its hosts.
s Communication between the controller and the devices in the subsystem.
s The state and I/O activity of the logical units, devices, and device ports in the
subsystem.
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
116 General Description
Disk Inline Exerciser
Use the disk inline exerciser (DILX) to investigate the data-transfer capabilities of
disk drives. DILX tests and verifies operation of the controller and the SCSI2 disk
drives attached to it. DILX generates intense read and write loads to the disk drive
while monitoring the drive's performance and status.
Configuration Utility
Use the configuration (CONFIG) utility to add one or more storage devices to the
subsystem. This utility checks the device ports for new disk drives, then adds them to
the controller's configuration and automatically names them.
HSUTIL
Use HSUTIL to upgrade the firmware on disk drives in the subsystem and to format
disk drives.
Code Load and Code Patch Utility
Use the Code Load/Code Patch (CLCP) utility to upgrade the controller software and
the EMU software. You can also use it to patch the controller software. Whenever you
install a new controller, you must have the correct software version and patch number.
IMPORTANT: Only Compaq field service personnel are authorized to upload EMU
microcode updates. Contact the Customer Service Center (CSC) for directions in
obtaining the appropriate EMU microcode and installation guide.
Clone Utility
Use the Clone utility to duplicate the data on any unpartitioned mirrorset. Back up the
cloned data while the actual storageset remains online.
117
Field Replacement Utility
Use the field replacement utility (FRUTIL) to replace a failed controller (in a dual-
redundant configuration) without shutting down the subsystem.You can also use this
menu-driven utility to replace cache modules, external cache batteries, and the PVA
module.
Change Volume Serial Number Utility
Only Compaq authorized service personnel may use this utility.
The Change Volume Serial Number (CHVSN) utility generates a new volume serial
number (called VSN) for the specified device and writes it on the media. It is a way to
eliminate duplicate volume serial numbers and to rename duplicates with different
volume serial numbers.
Device Statistics Utility
The Device Statistics (DSTAT) utility allows you to log I/O activity on a controller
over an extended period of time. Later, you can analyze that log to determine where
the bottlenecks are and how to tune the controller for optimum performance.
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
118 General Description
Cache Module
Each controller requires a companion cache module as shown in Figure 18.
Table 17 lists the descriptions and part numbers of the cache module. Figure 16 on
page 113 shows the location of a controller's companion cache module.
The cache module, which contains up to 512 MB of memory, increases the
subsystem's I/O performance by providing read, read-ahead, write-through, and
write-back caching. The size of the memory contained in the cache module depends
on the configuration of the DIMMs, with the supported combinations shown in
Table 16. For placement of the DIMMs, see the HSZ80 Array Controller ACS
Version 8.3 Maintenance and Service Guide.
Table 16 Cache Module Memory Configurations
DIMMs Quantity Memory
32 MB 2 64 MB
32 MB 4 128 MB
128 MB 2 256 MB
128 MB 4 512 MB
119
5
4
1
~
2
3
CXO6306B
Figure 18. Cache Module
Table 17 Location of Cache Module Parts
Item Description
Cache memory power LED
ECB Y cable
Release lever
Backplane connector
DIMM
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
120 General Description
Caching Techniques
The cache module supports the following caching techniques to increase the
subsystem's read and write performance:
s Read caching
s Read-ahead caching
s Write-through caching
s Write-back caching
Read Caching
When the controller receives a read request from the host, it reads the data from the
disk drives, delivers it to the host, and also stores the data in its cache module. This
process is called read caching.
Read caching can decrease the subsystem's response time to many of the host's read
requests. If the host requests some or all of the cached data, the controller satisfies the
request from its cache module rather than from the disk drives. By default, read
caching is enabled for all storage units.
To set the maximum cache that can be transferred, see "SET unit-number" in
Chapter 5, "CLI Commands."
Read-Ahead Caching
Read-ahead caching begins once the controller has already processed a read request
and it receives a sequential read request from the host. If the controller does not find
the data in the cache memory, it reads the data from the disks and sends it to the cache
memory.
121
The controller then anticipates subsequent read requests and begins to prefetch the
next blocks of data from the disks as it sends the requested read data to the host. This
is a parallel action. The controller notifies the host of the read completion, and
subsequent sequential read requests are satisfied through the cache memory. By
default, read-ahead caching is enabled for all disk units.
Write-Through Caching
When the controller receives a write request from the host, it stores the data in its
cache module, writes the data to the disk drives, then notifies the host when the write
operation is complete. This process is called write-through caching because the data
actually passes through--and is stored in--the cache memory on its way to the disk
drives.
If you enable read caching for a storage unit, write-through caching is automatically
enabled. Likewise, if you disable read caching, write-through caching is
automatically disabled.
Write-Back Caching
This caching technique decreases the subsystem's response time to write requests by
allowing the controller to declare the write operation "complete" as soon as the data
reaches its cache memory. The controller performs the slower operation of writing the
data to the disk drives at a later time.
By default, write-back caching is enabled for all disk units. In either case, the
controller will not provide write-back caching to a unit unless the cache memory is
nonvolatile, as described in the next section.
If the mirrorset is a disaster-tolerant mirrorset, then write-back caching cannot be
enabled.
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
122 General Description
Fault-Tolerance for Write-Back Caching
The cache module supports nonvolatile memory and dynamic cache policies to
protect the availability of its unwritten (write-back) data.
Nonvolatile Memory
Except for disaster-tolerant supported mirrorsets, the controller can provide write-
back caching for storage units as long as the controller's cache memory is nonvolatile.
In other words, to enable write-back caching, you must provide a backup power
source to the cache module to preserve the unwritten cache data in the event of a
power failure. If the cache memory were volatile--that is, if it didn't have a backup
power supply--the unwritten cache data would be lost during a power failure.
By default, the controller expects to use an ECB as the backup power source for its
cache module. See "External Cache Battery," page 129, for more information on the
ECB.
However, if your subsystem is backed up by an uninterruptible power supply (UPS),
you can tell the controller to use the UPS as the backup power source with the
command, SET Controller, and using the CACHE_UPS switch.
Cache Policies Resulting from Cache Module Failures
If the controller detects a full or partial failure of its cache module or ECB, it
automatically reacts to preserve the unwritten data in its cache module. Depending
upon the severity of the failure, the controller chooses an interim caching technique--
also called the cache policy--which it uses until you repair or replace the cache
module.
Table 18 shows the cache policies resulting from a full or partial failure of cache
module A in a dual-redundant controller configuration. The consequences shown in
this table are the same for cache module B.
123
Table 19 shows the cache policies resulting from a full or partial failure of cache
module A's ECB in a dual-redundant controller configuration. When cache module A
is at least 50% charged, the ECB is still good and is charging. When it is less than
50% charged, the ECB is low, but still charging. The consequences shown are the
opposite for a failure of cache module B's ECB.
Table 18 Cache Policies and Cache Module Status
Cache Module Status Cache Policy
Cache A Cache B Unmirrored Cache Mirrored Cache
Good Good Data loss: No. Data loss: No.
Cache policy: Both controllers Cache policy: Both controllers support
support write-back caching. write-back caching.
Failover: No. Failover: No.
Data loss: No. Controller A recovers its
Multibit Good Data loss: Forced error and loss of
lost write-back data from the mirrored
cache write-back data for which the
copy on cache B.
memory multibit error occurred. Controller A
failure detects and reports the lost blocks. Cache policy: Both controllers support
write-back caching.
Cache policy: Both controllers
support write-back caching. Failover: No.
Failover: No.
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
124 General Description
Table 18 Cache Policies and Cache Module Status (Continued)
Cache Module Status Cache Policy
Cache A Cache B Unmirrored Cache Mirrored Cache
Data integrity: Controller A recovers all
Good Data integrity: Write-back data that
DIMM or
of its write-back data from the
was not written to media when
cache
mirrored copy on cache B.
failure occurred was not recovered.
memory
controller Cache policy: Controller A supports
Cache policy: Controller A supports
chip write-through caching only; controller
write-through caching only;
failure B supports write-back caching.
controller B supports write-back
caching. Failover: In transparent failover, all
units failover to controller B and
Failover: In transparent failover, all
operate normally. In multiple-bus
units failover to controller B. In
failover with host-assist, only those
multiple-bus failover with host-
units that use write-back caching,
assist, only those units that use
such as RAIDsets and mirrorsets,
write-back caching, such as
failover to controller B.
RAIDsets and mirrorsets, failover to
controller B. All units with lost data
become inoperative until you clear
them with the CLEAR LOST_DATA
command. Units that didn't lose data
operate normally on controller B.
In single controller configurations,
RAIDsets, mirrorsets, and all units
with lost data become inoperative.
Although you can clear the lost data
errors on some units, RAIDsets and
mirrorsets remain inoperative until
you repair or replace the nonvolatile
memory on cache A.
125
Table 18 Cache Policies and Cache Module Status (Continued)
Cache Module Status Cache Policy
Cache A Cache B Unmirrored Cache Mirrored Cache
Cache Good Same as for DIMM failure. Data integrity: Controller A recovers all
Board of its write-back data from the
Failure mirrored copy on cache B.
Cache policy: Both controllers support
write-through caching only. Controller
B cannot execute mirrored writes
because cache module A cannot
mirror controller B's unwritten data.
Failover: No.
Table 19 Resulting Cache Policies and ECB Status
Cache Module Status Cache Policy
Cache A Cache B Unmirrored Cache Mirrored Cache
Data loss: No.
At least At least Data loss: No.
50% 50% Cache policy: Both controllers continue
Cache policy: Both controllers
charged charged to support write-back caching.
continue to support write-back
caching. Failover: No.
Failover: No.
Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
126 General Description
Table 19 Resulting Cache Policies and ECB Status (Continued)
Cache Module Status Cache Policy
Cache A Cache B Unmirrored Cache Mirrored Cache
Data loss: No.
| 355210-001
355222-001
355223-001
355224-001
387403-001
387404-001
388220-001
388221-001
388222-001
388700-001
388701-001
388709-001
388710-001
388711-001
388712-001
388713-001
388724-001
388725-001
388732-001
388733-001
AA-RC3CA-TE
AA-RF9TA-TE
AA-RF9XA-TE
AA-RF9YA-TE
AA-RF9ZA-TE
AA-RFADA-TE
AA-RFAEA-TE
AA-RFAFA-TE
AA-RFAKA-TE
AA-RFALA-TE
AA-RFAMA-TE
AG-RFA0A-BE
ed-write-ba
EK-BA370-UG
EK-H80RM-IC
EK-H8RMB-IC
EK-HSECB-IC
EK-HSXSW-WC
EK-HSZ80-CP
EK-HSZ80-MP
EK-HSZ80-RG
EK-HSZ80-SV
EK-RKTMP-TP
EK-SMCPR-UG
EK-SWXDT-OP
EK-SWXES-IG
XO-5135A-MC
XO-5172A-MC
XO-5316A-MC
|
