Digital Equipment DECmpp12000 User manual

DECmpp12000/SxModel100
ParallelDiskArray
ReferenceManual
Part Number: EK–DECAB–RM. B01
September 1992
This document provides a complete description of the DECmpp 12000/Sx
Parallel Disk Array hardware, its installation and service procedures.
Revision/Update Information: This document has been revised for
DECmpp Version 1.1.
Operating System and Version: ULTRIX Version 4.2A.
Future releases may require higher
versions.
Software Version: DECmpp 12000/Sx Version 1.1.
Digital Equipment Corporation
Maynard, Massachusetts

First Printing, January 1992
Revised, September 1992
The information in this document is subject to change without notice and should not be construed
as a commitment by Digital Equipment Corporation. Digital Equipment Corporation assumes no
responsibility for any errors that may appear in this document.
The software described in this document is furnished under a license and may be used or copied
only in accordance with the terms of such license.
NOTICE—Class A Computing Device:
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 computing device pursuant to Subpart
J or Part 15 of FCC rules, which are designed to provide reasonable protection against such radio
frequency interference when operated in a commercial environment. Operation of this equipment in
a residential area may cause interference; in which case, measures taken to correct the interference
are at the user’s expense.
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clause at DFARS 252.227-7013.
© Digital Equipment Corporation 1992.
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the MasPar logo. The following are trademarks of the MasPar Computer Corporation: MasPar
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MasPar Parallel Application Language (MPL), MasPar Parallel Disk Array (MPDA), and MasPar
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This document was prepared using VAX DOCUMENT, Version 2.0.

Contents
Preface ............................................................ ix
1 Parallel Disk Array Overview
1.1 Parallel Disk Array Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–5
1.1.1 DiskArrayController ..................................... 1–6
1.1.2 DAControllerBackplane................................... 1–8
1.1.3 DABackplane ........................................... 1–9
1.1.3.1 DA Controller Interconnect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–11
1.1.3.2 Disk Canister Interconnect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–11
1.1.3.3 MultiplexerInterconnect ................................ 1–11
1.1.3.4 LightpipeInterconnect.................................. 1–11
1.1.3.5 PowerInterconnect .................................... 1–11
1.2 DiskChassis ............................................... 1–12
1.2.1 DiskCanisters........................................... 1–12
1.2.2 MUXPrintedCircuitBoard................................. 1–13
1.2.2.1 DataMultiplexing ..................................... 1–13
1.2.2.2 WriteData........................................... 1–13
1.2.2.3 SectorPulseMonitor ................................... 1–13
1.3 DPU-PDAInterfaceCable ..................................... 1–13
1.4 Power/FanTray ............................................. 1–13
1.4.1 PowerSystem ........................................... 1–15
1.4.2 Power/FanTrayIndicators.................................. 1–16
1.4.3 ExhaustFan ............................................ 1–17
2 Parallel Disk Array Installation
2.1 Parallel Disk Array Site Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–1
2.1.1 PhysicalCharacteristics.................................... 2–1
2.1.1.1 Size and Service Clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–1
2.1.1.2 Weight.............................................. 2–1
2.1.2 Power and Cooling Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–1
2.1.3 Power and Environmental Specifications . . . . . . . . . . . . . . . . . . . . . . . 2–3
2.2 PDAInstallation ............................................ 2–4
2.2.1 Unpacking and Positioning the PDA . . . . . . . . . . . . . . . . . . . . . . . . . . 2–4
2.2.1.1 Assembling the Enclosure Skirts . . . . . . . . . . . . . . . . . . . . . . . . . . 2–6
2.2.2 ElectricalInstallation ..................................... 2–7
2.2.2.1 PrintedCircuitBoards.................................. 2–7
2.2.2.2 Installing Disk Array Controller PCBs . . . . . . . . . . . . . . . . . . . . . 2–8
2.2.3 InstallingMUXPCBs ..................................... 2–8
2.3 InstallingDiskCanisters...................................... 2–8
2.3.1 JumpersandTerminators .................................. 2–8
2.4 ConnectingDPUandPDA..................................... 2–11
2.4.1 InstallingtheDPUPCBs................................... 2–11
iii

2.5 SettingDPUJumpers ........................................ 2–15
2.6 TurningOntheDPUandPDA ................................. 2–17
3 Parallel Disk Array System Administration
3.1 Establishing PDA Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–2
3.2 ControllerConfiguration ...................................... 3–5
3.3 SettingUpFileSystems ...................................... 3–7
3.3.1 DefaultPartitions ........................................ 3–7
3.4 UpgradeProcedures.......................................... 3–8
3.4.1 Upgradingto8Disks...................................... 3–8
3.4.2 Upgradingto16Disks..................................... 3–8
4 Disk Formatting
4.1 TheFORMATCommand ...................................... 4–1
4.1.1 OperationExamples....................................... 4–3
4.1.1.1 BringUpaNewBank.................................. 4–3
4.1.1.2 Bringing Up a New Bank with Flaw Data on Host . . . . . . . . . . . . 4–3
4.1.1.3 Formatting Newly Installed Disks Within an Online/Mounted
Bank ............................................... 4–3
4.1.1.4 Reformatting Online/Mounted Banks with Growth Errors
Logged.............................................. 4–4
4.2 TheMOUNTBANKCommand.................................. 4–4
4.3 TheRECONSTRUCTCommand ................................ 4–5
4.3.1 Disabling and Replacing a Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4–6
4.3.2 AssigningaStandbyDrive.................................. 4–6
4.3.3 ReconstructingaDrive..................................... 4–6
4.4 TheSCRUBCommand........................................ 4–8
4.5 TheSPECIFYFLAWCommand ................................. 4–9
5 Removal and Replacement Procedures
5.1 Extending the DA Controller Chassis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5–3
5.2 Replacing DA Controller PCBs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5–5
5.3 ReplacingDiskCanisters...................................... 5–6
5.4 ReplacingMUXPCBs ........................................ 5–7
5.5 ReplacingtheLightpipePCB................................... 5–8
5.6 ReplacingPower/FanTray..................................... 5–9
5.7 Replacing Power Cables to the DA Backplane . . . . . . . . . . . . . . . . . . . . . . 5–12
5.8 ReplacingClockPCB......................................... 5–14
5.9 Replacing DA Controller Backplane Cabling . . . . . . . . . . . . . . . . . . . . . . . 5–15
5.9.1 Replacing PDA-DPU Interface Cable . . . . . . . . . . . . . . . . . . . . . . . . . . 5–15
5.9.2 Replacing Backplane Disk Cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5–17
5.10 Replacing the Lightpipe Signal Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5–18
5.11 Replacing Lightpipe Power Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5–19
5.12 Replacing Temperature Sensor Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5–20
iv

6 Parallel Disk Array Diagnostics
6.1 LightpipeIndicatorStatus..................................... 6–1
6.2 DiagnosticProcedures ........................................ 6–3
6.3 DiagnosticEnvironment....................................... 6–3
6.3.1 AutomaticMode.......................................... 6–4
6.4 VMEAdapterTests .......................................... 6–4
6.5 PDATestPrograms .......................................... 6–4
6.5.1 Internal DA Controller Test (da_intern) . . . . . . . . . . . . . . . . . . . . . . . . 6–4
6.5.2 Read/Write Configuration Test (da_config) . . . . . . . . . . . . . . . . . . . . . . 6–4
6.5.3 Read/Write Buffer Test (da_buff) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6–4
6.5.4 MountBankTest(da_mount)................................ 6–4
6.5.5 Read/SeekTest(da_seek)................................... 6–5
6.5.6 Read/Write Disk Test (da_disk) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6–5
6.6 DAControllerTests.......................................... 6–5
6.7 StatusOperations ........................................... 6–5
6.7.1 DiskErrorLogging ....................................... 6–5
6.7.2 ErrorInformation ........................................ 6–7
6.7.3 Extended Transfer Error Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6–9
6.7.4 Command/StatusSummary................................. 6–10
7 Upgrading the Parallel Disk Array
7.1 Upgrading to Eight Disk Drives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7–2
7.2 Upgrading to Sixteen Disk Drives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7–3
A Configuration Data
A.1 TheREADCONFIGCommand.................................. A–1
A.2 TheWRITECONFIGCommand................................. A–2
A.3 SystemConfigurationTable.................................... A–3
A.3.1 ControllerConfiguration ................................... A–4
A.3.2 Bank Control/Status Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . A–10
A.3.3 Disk Parameter Table Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A–15
A.3.4 BadBlockTable.......................................... A–18
A.3.5 Bank X, Disk X, System Area Configuration . . . . . . . . . . . . . . . . . . . . A–19
A.3.6 SystemAreaHomePage ................................... A–20
A.3.7 System Area RFT and GET Pages . . . . . . . . . . . . . . . . . . . . . . . . . . . . A–21
B Parallel Disk Array System Block Diagrams
B.1 Parallel Disk Array System Block Diagrams . . . . . . . . . . . . . . . . . . . . . . . B–1
C Recommended Spares List
D Disk Array Variations and Options
v

E Parallel Disk Array Reference Pages
dabinit(8).................................................. E–2
dabstat(8).................................................. E–3
dadisk(8) .................................................. E–4
dadsbl(8) .................................................. E–5
daflaw(8) .................................................. E–6
daformat(8) ................................................ E–8
dainit(8)................................................... E–10
damapchs(8)................................................ E–11
damount(8)................................................. E–12
darecon(8) ................................................. E–13
dascrub(8) ................................................. E–14
daspecflaw(8)............................................... E–16
dastat(8)................................................... E–17
dasubs(8) .................................................. E–18
daxformat(8)................................................ E–19
daxrdc(8) .................................................. E–20
daxscrub(8) ................................................ E–21
daxwrc(8).................................................. E–22
da_error_log(8).............................................. E–23
da_error_report(8) ........................................... E–24
Index
Figures
1–1 DECmpp 12000/Sx Parallel Disk Array . . . . . . . . . . . . . . . . . . . . . . . . 1–2
1–2 Parallel Disk Array, Model SMP11-AA . . . . . . . . . . . . . . . . . . . . . . . . . 1–3
1–3 Parallel Disk Array, Model SMP11-AB . . . . . . . . . . . . . . . . . . . . . . . . . 1–4
1–4 Parallel Disk Array, Model SMP11-AC . . . . . . . . . . . . . . . . . . . . . . . . . 1–5
1–5 DAControllerFrontPanel.................................. 1–6
1–6 DA Controller Slot Assignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–7
1–7 DAControllerBackplane................................... 1–8
1–8 DA Drive Backplane (front) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–9
1–9 DADriveBackplane(rear).................................. 1–10
1–10 DiskDriveCanister....................................... 1–12
1–11 Power/FanTray .......................................... 1–14
1–12 PowerBridgeandCables................................... 1–16
1–13 Power/Fan Tray Service Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–16
2–1 Parallel Disk Array Enclosure Dimensions . . . . . . . . . . . . . . . . . . . . . 2–2
2–2 Removing Enclosure Shipping Bracket . . . . . . . . . . . . . . . . . . . . . . . . 2–4
2–3 PDAEnclosureLevelers.................................... 2–5
2–4 FrontandSideSkirts ..................................... 2–6
2–5 RearSkirt .............................................. 2–7
2–6 Disk Drive PCB (Component Side) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–10
2–7 InsertingDiskCanister .................................... 2–11
vi

2–8 DPUCardCage.......................................... 2–12
2–9 DA Interface PCB Cable Connections . . . . . . . . . . . . . . . . . . . . . . . . . 2–13
2–10 Data Parallel Unit Card Cage Slots . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–14
2–11 DPU Backplane Jumper Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–16
5–1 PDAEnclosure(rear)...................................... 5–2
5–2 Extending the Disk Array Controller . . . . . . . . . . . . . . . . . . . . . . . . . . 5–4
5–3 Replacing the DA Controller PCB . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5–5
5–4 Power/FanTray(rear) ..................................... 5–10
5–5 Replacing the Power/Fan Tray . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5–11
5–6 PowerBridgeandCables................................... 5–13
5–7 ReplacingtheClockPCB................................... 5–14
6–1 PDAFrontIndicators...................................... 6–2
B–1 FullSystemBlockDiagram................................. B–1
B–2 Disk Array Controller Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . B–2
B–3 Disk Array Backplane Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . B–2
Tables
1RelatedDocuments ....................................... x
1–1 PDAConfigurations....................................... 1–2
1–2 DABackplaneConnectors .................................. 1–10
1–3 PowerSystemCapabilities.................................. 1–15
1–4 Backplane Power Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–15
1–5 Power/Fan Tray Service Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–17
2–1 PDASpecifications........................................ 2–3
4–1 BankConfigurations ...................................... 4–7
6–1 DiagnosticPrograms ...................................... 6–3
6–2 StatusBitDefinitions ..................................... 6–7
6–3 Command-Related Error Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6–10
A–1 READCONFIG Command Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A–2
A–2 System Configuration Byte Organization . . . . . . . . . . . . . . . . . . . . . . . A–3
A–3 Controller Configuration Block Byte Organization . . . . . . . . . . . . . . . . A–4
A–4 Controller Configuration Block Bit Description . . . . . . . . . . . . . . . . . . A–5
A–5 Disk Error Log Select Bit Descriptions . . . . . . . . . . . . . . . . . . . . . . . . A–7
A–6 32-Byte Bank Control/Status Block . . . . . . . . . . . . . . . . . . . . . . . . . . . A–10
A–7 #2 Byte Bank Control/Status Block Description . . . . . . . . . . . . . . . . . . A–11
A–8 Error Checking and Correcting Bit Descriptions . . . . . . . . . . . . . . . . . A–13
A–9 BitStatusandConditions .................................. A–14
A–10 Disk Parameter Table Byte Organization . . . . . . . . . . . . . . . . . . . . . . A–15
A–11 Drive Type and Flag Bit Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . A–16
A–12 Values for Disk Parameter Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A–17
A–13 Bad Block Table Byte Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . A–18
A–14 Home Page Byte Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A–20
A–15 Home Page Byte Group Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . A–20
C–1 ParallelDiskArrayRSL ................................... C–1
D–1 DECmpp Disk Array Variations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D–1
vii

Preface
The SMP11-Ax Parallel Disk Array (PDA) is a random access, hard disk storage
device designed to complement the DECmpp 12000/Sx and DECmpp 12000–LC/Sx
Series Massively Parallel Processing systems.
This document provides a description of the Parallel Disk Array hardware
and how to install and service it. Anyone who services the PDA and needs to
replace any components in it should read this manual and be familiar with the
procedures.
Intended Audience
This guide is for use by Digital Services personnel and by self-maintenance
customers who will be servicing the PDA system. It may also be used by PDA
system administrators.
Document Structure
This manual contains seven chapters and five appendixes:
• Chapter 1 is a general overview of the PDA configurations and components.
• Chapter 2 contains installation procedures, including connecting the PDA to
the DECmpp 12000/Sx system data parallel unit (DPU) and powering up the
PDA.
• Chapter 3 describes system administration procedures for bringing the PDA
online.
• Chapter 4 explains the disk formatting instructions.
• Chapter 5 explains how to replace the various PDA field replaceable units.
• Chapter 6 explains the indicator display and the diagnostic procedures and
tests.
• Chapter 7 describes procedures for upgrading the PDA to larger storage
configurations.
• Appendix A contains PDA configuration data tables.
• Appendix B contains system block diagrams.
• Appendix C lists the PDA recommended spare parts.
• Appendix D lists PDA option variants.
• Appendix E contains PDA-specific reference pages.
ix

Related Documents
Table 1 is a list of documents that provide additional information about the PDA
and the DECmpp 12000/Sx system.
Table 1 Related Documents
Document Title Order Number
DECmpp 12000/Sx System Overview Manual AA-PMAPB-TE
DECmpp 12000/Sx System Administration Guide AA-PKU3C-TE
DECmpp 12000/Sx Parallel VME Reference Manual EK-DECAB-PM
DECmpp 12000/Sx Hardware Installation Guide EK-DECAC-IG
x

Conventions
The following conventions are used throught the DECmpp 12000/Sx
documentation set.
Convention Meaning
Return In examples, a key name shown within a box indicates that
you press a key on the keyboard. In text, a key name is not
enclosed in a box but is printed with an initial capital letter,
like Return.
Ctrl/xA key combination, shown with a slash separating the two key
names, indicates that you hold down the first key while you
press the second key.
MB1, MB2, MB3 The buttons on a mouse. MB1 is the left button, MB2 is the
center button, and MB3 is the right button of a mouse whose
button arrangement is right-handed. It is possible to redefine
the mouse buttons.
% A percent sign (%) represents the default user prompt for your
system.
# A number sign (#) represents the default superuser (root)
prompt for your system.

In examples, a horizontal series of dots, or ellipsis, indicates
that additional parameters, values, or other information can be
entered.
.
.
.In examples, a vertical series of dots, or vertical ellipsis,
indicates that a portion of the example is intentionally omitted.
[ ] In syntax descriptions and functional descriptions, brackets
indicate optional items.
dpumanager(6) Cross-references to the ULTRIX Reference Pages, which include
the appropriate section number in parentheses.
italicized text In examples, italicized text denotes parameters, values, or
other information that will change from either session to
session or user to user. In text, italicized words or phrases are
used to add emphasis to important words, concepts, or titles of
manuals.
ULTRIX keywords This typeface is used to indicate system output or the exact
name of a command, option, partition, pathname, directory, or
file.
Code examples This typeface is used to display program coding examples.
UPPERCASE and
lowercase strings The ULTRIX system differentiates between lowercase and uppercase characters. Literal strings that appear in text,
examples, syntax descriptions, and function descriptions must
be entered exactly as shown.
xi

Three types of notes are used in this manual:
•Note
Gives additional information or information particularly important to the
procedure.
•Caution
Indicates potential damage to equipment or data.
•Warning
Indicates potential injury to a person.
xii

1
Parallel Disk Array Overview
The DECmpp 12000/Sx system includes a massively parallel, data-parallel
processor (the data parallel unit, or DPU) and a front-end server (scalar)
processor running ULTRIX. In a separate enclosure connected to the DPU, the
Parallel Disk Array (PDA), shown in Figure 1–1, provides a parallel, multidisk
architecture, consisting of a disk array (DA) controller and an array of disk
drives providing the bulk data storage. The disk array comprises 5-1/4 inch ESDI
disk drives, arranged in banks of 4, 8, or 16 data disks, with up to 2 associated
parity disks. An optional feature is a single hot standby disk, enhancing the PDA
fault-tolerant operation.
The disk array is a scalable I/O device for bulk data storage. (Architecturally,
it is similar to a conventional BSD 4.2 UNIX file system.) The DA controller
provides a high-speed data connection to the disk array. A VME control port
allows an external VME agent to perform additional basic control functions. A
diagnostic port allows for debugging. Front panel indicators provide status for
both DA system power and individual disks.
The PDA provides the DECmpp 12000/Sx with parallel access to large data files
and is fault-tolerant, using parity disks and 48-bit error correction code (ECC) on
each disk. Failed disks can be replaced during system operation, and the PDA
minimizes performance degradation on active disks while reconstructing data on
the new disk.
The PDA treats the entire disk array as a single, logical storage device. You can
create individual files of up to 2 Gbytes. Many smaller files may be stored across
multiple disks. Each formatted data disk provides 1.45 Gbytes of storage, with
up to 23 Gbytes of formatted capacity in a 16-disk configuration.
Disk-drive replacement procedures and configuration upgrades require a
minimum amount of effort. Each disk drive is in a modular disk canister, which
is easily installed or removed. The canisters in one configuration can often be
reused in a larger system, and most canisters do not have to be moved from their
current positions.
The chassis for expansion to a full complement of disk drive canisters is included
in all PDA configurations to permit ease of upgrading storage capacity.
Table 1–1 describes the three PDA configurations. These configurations are
shown in Figure 1–2, Figure 1–3, and Figure 1–4.
Parallel Disk Array Overview 1–1

Figure 1–1 DECmpp 12000/Sx Parallel Disk Array
MKV-040000314-82-DG
Table 1–1 PDA Configurations
MODEL SMP11-AA SMP11-AB SMP11-AC
Disk Banks 1 1 2
Data + Parity Disks 4 + 1 8 + 1 16 + 2
Total Disks 5 9 18
Hot Standby (optional) 1 1 1
Total Unformatted
Capacity 6 Gbytes 12 Gbytes 24 Gbytes
Total Formatted Capacity 5.8 Gbytes 11.5 Gbytes 23 Gbytes
1–2 Parallel Disk Array Overview

Figure 1–2 Parallel Disk Array, Model SMP11-AA
Bank 1
Power/Fan Tray
Backplane
Array
Controller
Array
Controller
FRONT SIDE REAR
MUX PCB
Drive
Canisters
Disk Disk
P 8 6 4 2
S
MKV-040000314-70-MPS
Standby
Drive
Optional
Bank 2
Parallel Disk Array Overview 1–3

Figure 1–3 Parallel Disk Array, Model SMP11-AB
Bank 2
Power/Fan Tray
Backplane
Array
Controller
Array
Controller
FRONT SIDE REAR
MUX PCB
Drive
Canisters
Drive
Canisters
S 7 5 3 1
P 8 6 4 2
MKV-040000314-71-MPS
Disk Disk
Standby
Drive
Optional
Bank 1
1–4 Parallel Disk Array Overview

Figure 1–4 Parallel Disk Array, Model SMP11-AC
Bank 1
Power/Fan Tray
Backplane
Array
Controller
Array
Controller
Bank 2
MUX PCB
Drive
Canisters
Drive
Canisters
Drive
Canisters
Drive
Canisters
FRONT SIDE REAR
Disk Disk
1 3 5 7
2 4 6 8 P 
S 7 5 3 1
P 8 6 4 2
Optional
Standby
Drive
MKV-040000314-72-MPS
1.1 Parallel Disk Array Components
The PDA has the following major components, which are described individually
in more detail in the sections that follow:
• Disk array controller — Contains printed circuit boards (PCBs) controlling
data and parity disk drives; provides a link to the DPU backplane through
the controller’s CPU PCB
• Disk array backplane — Provides power and signal interconnects between
disk canisters and DA controller backplane
• Disk chassis — Contains banks of disk canisters
• Power/fan tray — Contains DC power supplies and a cooling fan
The disk array (DA) controller chassis mounts in the upper-front area of the
PDA enclosure. The disk drive/canister chassis and DA backplane mounts in the
middle of the enclosure. It is 38.86 cm (15.3 inches) high, 48.26 cm (19 inches)
wide, and 0.32 cm (0.125-inch) thick.
The power/fan tray at the bottom of the enclosure contains the DC power supply
and the cooling fan.
Parallel Disk Array Overview 1–5

1.1 Parallel Disk Array Components
1.1.1 Disk Array Controller
The intelligent DA disk controller stores and retrieves data from banks of either
four or eight data disks through printed circuit board (PCBs) connected to
its embedded backplane. Each data PCB can control up to three data disks.
Depending on the configuration, the DA controller can have up to 8 PCBs
controlling up to two banks of data disks; a bank can have four or eight data
disks. Each bank also has one parity disk to support the data disks.
Figure 1–5 shows the DA controller indicators and connectors:
• 10 disk indicators — red during initialization; green when the disk is on line
• Ready indicator (CPU PCB) — red during initialization; green when the
controller is on line
• Reset switch — Forces a powerup system reset (never used during normal
operation)
• Com port — RS-232 serial communication port for offline diagnostics, online
system configuration, maintenance, and controller status monitoring
Figure 1–5 DA Controller Front Panel
DATA
COM
PORT
RESET
READY
1 2 3 4 5 6 7 8 PAR STDBY
Remove 2 Screws
to Access PCBs
Loosen 2 Screws
to Access PCBs
MKV-040000314-100-MPS
1–6 Parallel Disk Array Overview

1.1 Parallel Disk Array Components
Figure 1–6 shows the PCB slot assignments in the DA controller backplane:
• Slots 1—8: Disk control PCBs
• Slot 9: Parity disk PCB
• Slot 10: Standby disk PCB
• Slot 11: Parity PCB
• Slot 12: Central processing unit (CPU) PCB
The DA controller integrates a master, high-speed interface (HSI) unit on the
CPU and Parity PCBs.
The DA controller mounts on the PDA enclosure rails with slide guides. Hinges
allow the fully extended DA controller to rotate forward 90 degrees, providing
access to its backplane and connectors. The DA controller is 38.1 cm (15 inches)
high, 42.55 cm (16.75 inches) wide, and 28.58 cm (11.25 inches) deep. Two 4-1/4
inch fans mounted on top of the DA controller card cage provide cooling for the
DA controller PCBs.
Figure 1–6 DA Controller Slot Assignments
COM Port
Reset Switch
Disk Control PCBs
Standby Disk PCB
Parity Disk PCB Parity PCB CPU PCB
(Optional)
MKV-040000314-73-MPS
Parallel Disk Array Overview 1–7

1.1 Parallel Disk Array Components
1.1.2 DA Controller Backplane
The DA controller backplane (Figure 1–7) has the following connector blocks:
• A1—A10: 34-pin control cable (40-pin connector) to DA backplane connectors
JnP1
• B1—B10: 20-pin data cable to DA backplane connectors JnP2
• A12: 50-pin cable connector conveying control information (command/status)
to/from DA interface PCB in DPU
• B11: 50-pin cable connector conveying data to/from DA interface PCB in DPU
Behind the DA controller, two cable clamps and a gravity guide bar hold the
cables to the DA backplane in place and support the cable slack necessary to
allow the DA controller to rotate forward.
Figure 1–7 DA Controller Backplane
10987654321
CONTROL
10987654321
DATA
13 12 11
13 12 11
GND
+5
DC Power
MKV-040000314-74-MPS
B
A
1–8 Parallel Disk Array Overview