Seagate BARRACUDA ST11950N/ND/W/WD User manual

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BARRACUDA 1 and 2
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Disc Drive
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ST11950N/ND/W/WD
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ST12550N/ND/W/WD
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Installation Guide
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Contents
Preface .................................................................. 1
Electrostatic discharge protection........................... 1
Important safety information and precautions ......... 2
WichtigeSicherheitshinweise............................... 5
Technical support services..................................... 10
General description ................................................ 12
Initial setup information........................................... 19
Kühlung des Systems .......................................... 36
Installation des Laufwerkes
und Anschluß der Kabel....................................... 39
© 1994 Seagate Technology, Inc. All rights reserved
Publication Number: 83327770, Rev. D
June 1994
Seagate®,SeagateTechnology®,andtheSeagatelogo
are registered trademarks ofSeagateTechnology,Inc.
Barracuda™,SeaFAX™,SeaFONE™,SeaTDD™,and
SeaBOARD™aretrademarksof SeagateTechnology,
Inc.Otherproductnames areregisteredtrademarksor
trademarks of their owners.
No part of this publication may be reproduced in any
formwithoutwrittenpermissionfromSeagateTechnol-
ogy, Inc.

ST11950 and ST12550 Installation Guide, Rev. D 1
Preface
This manualcontains information for users of the
Seagate®ST11950N/ND,ST11950W/WD, ST12550N/ND,
and ST12550W/WD Barracuda™ SCSI disc drives. It
providessupportservices,performancespecifications,
and initial setup information. Additional information is
availableinthe Barracuda1and2ProductManual (part
number 83327780). Contact your Seagate sales rep-
resentative if you need to order this publication.
Electrostatic discharge protection
Caution. Removal of circuit boards by personnel not
performing depot repair will damage compo-
nents and may void the warranty.
All drive electronic assemblies are sensitive to static
electricity,duetotheelectrostaticallysensitivedevices
used within the drive circuitry. Although some devices
such asmetal-oxide semiconductors are extremely
sensitive, all semiconductors, as well as some resis-
tors and capacitors, may be damaged or degraded by
exposure to static electricity.
Electrostatic damage to electronic devices may be
caused by the direct discharge of a charged conductor
or by exposure to the static fields surrounding charged
objects.Toavoiddamagingdriveelectronicassemblies,
observe the following precautions when installing or
servicing the drive:

2ST11950 and ST12550 Installation Guide, Rev. D
•Ground yourself to the drive whenever the drive elec-
tronics are or will be exposed. Connect yourself to
ground with a wrist strap (Seagate part number
12263496).Connectionmaybemadetoanygrounded
metalassembly.Asageneralrule,rememberthatyou
andthedriveelectronicsmustallbegroundedtoavoid
potentially damaging static discharges.
•TurnoffthepowerbeforeremovingorinstallingtheDC
power cable.
•Do not remove any circuit boards from the drive.
•Never use an ohmmeter on any circuit boards.
Important safety information and precautions
Caution. Useforced-airventilationwhenbench-testing
the drive to ensure proper cooling of drive
components.
Usepropersafetyandrepairtechniquesforsafe,reliable
operation of this unit. Service should be done only by
qualifiedpersons.Werecommendtheproceduresinthis
manual as effective ways of servicing the unit. Some
procedures require the use of special tools. For proper
maintenance and safety, you must use these tools as
recommended.
The procedures in this manual and labels on the unit
contain warnings and cautions that must be carefully

ST11950 and ST12550 Installation Guide, Rev. D 3
read and followed to minimize or eliminate the risk of
personal injury. The warnings point out conditions or
practicesthatmayendangeryouorothers.Thecautions
point out conditions or practices that may damage the
unit, possibly makingit unsafe for use.
These warnings and cautions are not exhaustive. We
cannotpossiblyknow,evaluate,andadviseyouofallthe
ways in which maintenance might be performed or the
possibleriskofeachtechnique.Consequently,wehave
not completed any such broad evaluation. If you use a
non-approved procedure or tool, first ensure that the
methodyouchoosewillnotriskeitheryoursafetyorunit
performance.
Alwaysobservethefollowingwarningsandprecautions:
•Performallmaintenancebyfollowingtheproceduresin
this manual.
•Follow all cautions and warnings in the procedures.
•Use sound safety practices when operating or repair-
ing the unit.
• Use caution when troubleshooting a unit that has
voltages present. Turn off power to the unit before
servicing it.
•Wearsafety shoeswhenremovingorreplacingheavy
parts.

4ST11950 and ST12550 Installation Guide, Rev. D
•Ensure that the internal temperature of the rack or
cabinetdoesnotexceedthelimitsdefinedforthedrive
when the drive is mounted in an equipment rack or
cabinet. When units are stacked vertically, pay atten-
tiontothetopwheretemperaturesareusuallyhighest.
•Follow the precautions listed above in “Electrostatic
discharge protection.”
•Donot remove anycircuit boards fromthe drive chas-
sis.Returntheentiredrivefordepotrepairifanycircuit
board is defective. Removal of circuit boards by per-
sonnel not performing depot repair will damage com-
ponents and may void the warranty.
•Donotremovetheheadanddiscassembly(HDA)from
the drive chassis. Return the entire drive for depot
repair if the HDA is defective.
•Do not attempt to disassemble the HDA. It is not field
repairable. If the sealed HDA is opened by personnel
not performing depot repair, this will damage compo-
nents and void the warranty.
As a component, this drive is designed to be installed
and operated in accordance with UL1950, IEC950,
EN60950, CSA C22.2 950, and VDE0805.
Seagate takes all reasonable steps to ensure that its
products are certifiable to currently accepted stan-

ST11950 and ST12550 Installation Guide, Rev. D 5
dards. Typical applications of these disc drives include
customer packaging and subsystem design. Safety
agenciesconditionallycertifycomponentparts,suchas
theBarracuda discdrive, based on their final accept-
abilityintheend-useproduct.Thesubsystemdesigners
are responsible for meeting these conditions of accept-
abilityinobtainingsafety/regulatoryagencycompliance
in their end-use products and for certifying where
required by law. A necessary part of meeting safety
requirements is the provision for overcurrent protection
on drive SELV supply voltages.
This unit is a component assembly and as such is not
meant to comply with FCC or similar national require-
mentsasastand-aloneunit.Engineeringradiatedemis-
sions test results are available through the Seagate
Safety Department to assist the subsystem designer.
WichtigeSicherheitshinweise
Vorsicht. Beim Testen des Laufwerks auf dem
Prüftisch ist Fremdbelüftung vorzusehen, um eine
ausreichende Kühlung der Laufwerkkomponenten
sicherzustellen.
Verwenden Sie geeignete Sicherheits- und
Reparaturverfahren, um den sicheren, zuverlässigen
Betrieb dieser Einheit zu gewährleisten. Reparaturen

6ST11950 and ST12550 Installation Guide, Rev. D
dürfen nur von qualifiziertem Fachpersonal
vorgenommenwerden. Wir empfehlen die Verfahren in
diesem Handbuch als effektive Methoden zur
WartungundReparaturderEinheit.EinigeVerfahren
erfordern Spezialwerkzeuge; diese müssen zur
sachgemäßenAusführungderWartungsarbeitenund
aus Sicherheitsgründen den Empfehlungen
entsprechend verwendet werden.
Die Verfahren in diesem Handbuch und die Aufkleber
aufdem Gerät enthalten Warn- undVorsichtshinweise.
Diese Hinweise sind sorgfältig durchzulesen und zu
beachten, um das Risiko von Verletzungen auf ein
Mindestmaß zu beschränken oder ganz zu vermeiden.
DieWarnhinweisemachenaufSituationenoderPraktiken
aufmerksam, die Sie oder andere gefährden könnten.
Die Vorsichtshinweise machen auf Situationen oder
Praktiken aufmerksam, die die Einheit beschädigen
können,so daß deren Gebrauchmit Risiko behaftet ist.
Die Warn- und Vorsichtshinweise sind nicht
allumfassend! Es ist uns einfach nicht möglich, alle
WartungsmethodenoderdieeventuellenRisikenjeder
Methode zu kennen, zu beurteilen und Sie
entsprechend zu beraten. Aus diesem Grund haben
wir auf eine derartige umfassende Beurteilung
verzichtet. Falls Sie ein hier nicht beschriebenes
Verfahren oder Werkzeug verwenden, stellen Sie

ST11950 and ST12550 Installation Guide, Rev. D 7
zuerstsicher,daßdasgewählteVerfahrenwederIhre
persönliche Sicherheit noch die Leistung der Einheit
gefährdet.
Beachten Sie in jedem Fall die folgenden Warn-und
Vorsichtshinweise:
• Führen Sie alle Wartungsarbeiten entsprechend den
Anweisungen in diesem Handbuch aus.
•Beachten Sie alle Warn- und Vorsichtshinweise in
diesem Handbuch.
•Treffen Sie beim Betrieb oder bei der Reparatur der
Einheitangemessene Sicherheitsvorkehrungen.
•Wenn eine Einheit unter Spannung steht, gehen Sie
bei der Fehlerdiagnose besonders vorsichtig vor.
Schalten Sie die Einheit aus, bevor Sie mit den
Reparaturarbeitenbeginnen.
•Tragen Sie Sicherheitsschuhe, wenn Sie schwere
Teile aus- bzw. einbauen.
•Wenn das Laufwerk in einem Einbaugestell oder
Gehäuse montiert ist, sorgen Sie dafür, daß die
Temperatur im Inneren des Gestells oder Gehäuses
die für das Laufwerk vorgegebenen Grenzwerte nicht
übersteigt. Wenn Einheiten vertikal übereinander
betestigtwerden,achtenSiebesondersaufdenoberen
Stapelbereich,dadortdieTemperaturgewöhnlicham
höchsten ist.

8ST11950 and ST12550 Installation Guide, Rev. D
• Befolgen Sie die oben unter “Electrostatic Discharge
Protection”angegebenen Sicherheitsmaßnahmen.
•NehmenSiekeinePlatinenausdemLaufwerkgehäuse.
Wenn eine Platine defekt ist, muß das gesamte
Laufwerk zur Reparatur eingeschickt werden. Die
HerausnahmevonPlatinendurchanderePersonenals
diefürdiewerkseitigeReparaturzuständigenkannzu
einerBeschädigungderKomponentenundErlöschen
des Garantieanspruchs führen.
• Die vormontierte Kopf- und Festplatteneinheit (HDA)
nicht aus dem Laufwerkgehäuse nehmen! Falls die
HDA beschädigt ist, schicken Sie das gesamte
Laufwerk zur Reparatur ein.
•Die HDA ist nicht vor Ort reparierbar und darf nicht
auseinandergenommen werden! Öffnen der
versiegelten HDA durch andere Personen als die für
die werkseitige Reparatur zuständigen hat eine
Beschädigung der Komponenten und Erlöschen des
Garantieanspruchs zur Folge.
AlsTeilkomponente ist dieses Laufwerkfürdie Installa-
tion und den Betrieb in Übereinstimmung mit UL 1950,
IEC950, EN60950, CSA C22.2 950 und VDE0805
vorgesehen.
Seagate ist ständig bemüht, die Zulassungsfähigkeit
von Seagate-Produkten im Rahmen der gegenwärtig

ST11950 and ST12550 Installation Guide, Rev. D 9
geltendenStandardszugewährleisten.Zudentypischen
Anwendungen dieser Festplattenwerke zählen
Systemeinbau durch den Kunden und die Konstruktion
vonUntersystemen.Sicherheitsbehördengewähreneine
bedingte Zulassung für Komponenten wie das Barra-
cuda-Festplattenlaufwerkvorbehaltlichderendgültigen
ZulasssungimEndprodukt.DesignervonUntersystemen
sind dafür verantwortlich, die Voraussetzungen für die
Einhaltung sicherheits- oder aufsichtsbehördlicher
VorschrifteninihrenEndproduktenund-fallsgesetzlich
vorgeschrieben - für die Zulassung zu schaffen.
Eine Grundvoraussetzung zur Einhaltung der
Sicherheitsanforderungen ist die Bereitstellung
eines Überlastschutzes für die SELV-
Versorgungsspannungen des Laufwerks.
DiesesGerätist eineBaugruppeundunterliegtals
solchenichtdenAnforderungenderFCCoderähnlicher
nationaler Behörden für eigenständige Geräte.
TechnischeTestergebnissezuelektromagnetische
Strahlung sind für Designer von Untersystemen auf
Anfrage von der Seagate-Sicherheitsabteilung
erhältlich.

10 ST11950 and ST12550 Installation Guide, Rev. D
Technical support services
Seagate Technology provides technical support litera-
ture and diagnostic utilities to authorized distributors.
Please contact your dealer for technical support and
installationtroubleshooting.Producttechnicalsupport
is available for all Seagate products by calling the
SeaFAX™,SeaFONE™,SeaTDD™,orSeaBOARD™
services. These are toll calls if you dial from outside of
the number’s local dialing area.
SeaFAX
USA [phone]; England 44-62-847-7080
Use a touch-tone telephone to access Seagate’s auto-
mated FAX system and select technical support infor-
mationbyreturnFAX.Thisserviceisavailable24hours
a day, 7 days a week.
SeaFONE [phone]
Technical support specialists are available from 8:00
A.M.to 5:00P.M.PST,MondaythroughFriday.Recorded
technical information on selected Seagateproducts is
providedwhile youareon hold. Recordings areacces-
sible 24 hours a day, 7 days a week.
SeaTDD [phone]
TDD is a telecommunication device for the deaf where
two people can communicate using a keyboard that is
connectedtothephoneline.ATDDdeviceisrequiredto

ST11950 and ST12550 Installation Guide, Rev. D 11
access this service, which is available from 8:00 A.M. to
5:00 P.M.PST, Monday through Friday.
SeaBOARD
The Seagate Technical Support Bulletin Board System
(BBS) is accessible by modem 24 hours a day, 7 days
a week. The communications software must be set for
eight data bits, no parity, and one stop bit (8N1). These
BBS numbers operate at 9600 baud max. With this
service you can access:
•Specifications and jumper configurations for Seagate
products
•Reprints of Seagate documentation
•A directory of information and helpful utilities that you
can download to your own computer
Telephone
Location number
USA, Mexico, Latin America [phone]
England 44-62-847-8011
Germany 49-89-140-9331
Singapore 65-292-6973
Australia 61-2-756-2359
Canada [phone]
France 33-1-40-67-1034
Korea 82-2-556-7294

12 ST11950 and ST12550 Installation Guide, Rev. D
General description
Barracuda 1 and 2 SCSI disc drives are high-speed,
random-access digital-data storage devices. The
ST11950N/ND and ST12550N/ND drives are illustrated
inFigure1,andtheST11950W/WDandST12550W/WD
drives are illustrated in Figure 2. Specifications and DC
power requirements for the drive are listed in tables
following the figure.
Thedriveisacomponentforinstallationinanenclosure
designed for the drive. This is often a rack within the
systemor anexternalenclosuredesignedto houseone
or more disc drives or other peripheral units. In either
case,thediscdrivemustreceiveadequatecooling(refer
to “Providing adequate cooling”) and it must be suffi-
ciently grounded and shielded from emissions. The
Barracuda 1 and 2 Product Manual (part number
83327780)containsguidelinesforaproperlydesigned
enclosure.

ST11950 and ST12550 Installation Guide, Rev. D 13
I/O Terminator Packs
(single-ended I/O only)
SCSI I/O
Connector
DC Power Connector
J4 J01
Figure 1. Barracuda 1 and 2 disc drive (N/ND type)
SCSI I/O
Connector
DC Power
Connector
J4 J01
Pin 1
J5
Figure 2. Barracuda 1 and 2 disc drive (W/WD type)

14 ST11950 and ST12550 Installation Guide, Rev. D
Characteristics ST11950N/ND ST11950W/WD
Interface Fast SCSI-21Fast & Wide SCSI-21
Multi-seg. cache 1,024 Kbytes 1,024 Kbytes (W)
512 Kbytes (WD)
Capacity
Unformatted 2,030 Mbytes 2,030 Mbytes
Formatted21,690 Mbytes 1,690 Mbytes
Recording
Cylinders (user) 2,706 2,706
Heads 15 15
Avg sectors/track 81 (51h) 81 (51h)
Avg bytes/track 49,768 49,768
Modulation RLL 1,7 code RLL 1,7 code
SCSI rate
Max burst transfer 10 Mbytes/sec 20 Mbytes/sec
Seek time3
Average read 8.0 msec 8.0 msec
Average write 9.0 msec 9.0 msec
Disc rotation
RPM 7,200 7,200
Average latency 4.17 msec 4.17 msec
1Can also be operated according to SCSI-1 protocol.
2Standard factory units are formatted as follows:
512 data bytes per sector, 6 spare sectors per cylinder
1 cylinder at the inner track reserved for spares
3Not including on-board controller overhead.

ST11950 and ST12550 Installation Guide, Rev. D 15
Characteristics ST12550N/ND ST12550W/WD
Interface Fast SCSI-21Fast & Wide SCSI-21
Multi-seg. cache 1,024 Kbytes 1,024 Kbytes (W)
512 Kbytes (WD)
Capacity
Unformatted 2,572 Mbytes 2,572 Mbytes
Formatted22,139 Mbytes 2,139 Mbytes
Recording
Cylinders (user) 2,707 2,707
Heads 19 19
Avg sectors/track 81 (51h) 81 (51h)
Avg bytes/track 49,768 49,768
Modulation RLL 1,7 code RLL 1,7 code
SCSI rate
Max burst transfer 10 Mbytes/sec 20 Mbytes/sec
Seek time3
Average read 8.0 msec 8.0 msec
Average write 9.0 msec 9.0 msec
Disc rotation
RPM 7,200 7,200
Average latency 4.17 msec 4.17 msec
1Can also be operated according to SCSI-1 protocol.
2Standard factory units are formatted as follows:
512 data bytes per sector, 9 spare sectors per cylinder
1 cylinder at the inner track reserved for spares
3Not including on-board controller overhead.

16 ST11950 and ST12550 Installation Guide, Rev. D
DC power requirements
for ST11950N/ND and ST12550N/ND drives
Single-ended Differential
++
++
+5V ++
++
+12V ++
++
+5V ++
++
+12V
Voltage regulation5±±
±±
±5% ±±
±±
±5%2±±
±±
±5% ±±
±±
±5%2
Amps
Maximum operating current11.1 0.95 1.5 0.95
Average idle current1, 12 0.76 0.83 0.79 0.83
Maximum starting current
Peak DC3, 61.0 2.18 1.1 2.18
Peak AC3−3.1 −3.1
Delayed motor start (max)1, 41.06 0.19 1.1 0.2
Peak operating current
Typ DC1,10 1.07 0.91 1.47 0.91
Max DC11.1 0.95 1.5 0.95
Max (peak) 1.15 1.87 1.8 1.86
Track following (DC)
at OD11.0 0.84 1.1 0.84
at ID11.0 0.9 1.1 0.9
Read track
OD DC1,14 1.1 0.85 1.6 0.85
AC 1.2 1.2 1.8 1.2
Seeking
Typical DC1, 13 1.0 1.2 1.1 1.2
Maximum DC11.1 1.2 1.2 1.2
Maximum (peak) AC 1.2 1.8 1.7 1.8

ST11950 and ST12550 Installation Guide, Rev. D 17
DC power requirements
for ST11950W/WD and ST12550W/WD drives
Single-ended Differential
++
++
+5V ++
++
+12V ++
++
+5V ++
++
+12V
Voltage regulation5±±
±±
±5% ±±
±±
±5%2±±
±±
±5% ±±
±±
±5%2
Amps
Maximum operating current11.04 0.95 1.3 0.95
Average idle current1, 12 0.76 0.83 0.83 0.83
Maximum starting current
Peak DC3, 61.0 2.18 1.1 2.18
Peak AC3−3.1 −3.1
Delayed motor start (max)1, 41.0 0.19 1.1 0.19
Peak operating current
Typ DC1,10 1.03 0.91 1.21 0.91
Max DC11.04 0.95 1.3 0.95
Max (peak) 1.2 1.87 2.0 1.87
Track following (DC)
at OD11.0 0.84 1.1 0.84
at ID11.0 0.9 1.1 0.9
Read track
OD DC1,15 1.1 0.85 1.4 0.85
AC 1.3 1.2 2.0 1.2
Seeking
Typical DC1, 13 1.0 1.2 1.1 1.2
Maximum DC11.1 1.2 1.2 1.2
Maximum (peak) AC 1.2 1.8 2.0 1.8
1Measured with an average reading DC ammeter. Instanta-
neous +12V current peaks will exceed these values.
continued

18 ST11950 and ST12550 Installation Guide, Rev. D
continued from previous page
2A −10% tolerance is permissible during initial start of the
spindlebutmust returnto ±5%beforereaching 7,200RPM.
The±5% mustbemaintainedafterthedrivesignifiesthatits
power-up sequence has been completed and that the drive
is able to accept selection by the hostinitiator.
3See the +12V current profile in the
Product Manual .
4This condition occurs when the Motor Start option is en-
abled and the drive has not yet received a start motor
command.
5See “Conducted noise immunity” in the
Product Manual.
The specified voltage tolerance is inclusive of ripple, noise,
and transient response.
6At power-up, the motor current regulator limits the +12V
current to an average value of less than 2.0A, although
instantaneous peaks may exceed this value. These peaks
should measure 5 msec duration or less.
7Minimumcurrent loadingfor each supplyvoltage isnot less
than 7% of the maximum operating current shown.
8Use separate ground returns for +5 and +12V supplies.
9Where power is provided to multiple drives from a common
supply, carefully consider individual-drive power require-
ments.Wheremultipleunitsarepoweredonsimultaneously,
besurethepeakstartingcurrentisavailabletoeachdevice.
10Operating condition is a third-stroke seek at OD and read
one track. The command is issued every 0.07 seconds.
continued