seagate ST12450W Installation guide

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Barracuda 2, 2HP Disc Drive

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ST12450W/WD

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Product Manual, Volume 1

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Barracuda 2, 2HP Disc Drive

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ST12450W/WD

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Product Manual, Volume 1

○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○

© 1994 Seagate Technology, Inc. All rights reserved
Publication number: 83328900, Rev. B
October 1995

Seagate®, Seagate Technology®, and the Seagate logo are registered
trademarks of Seagate Technology, Inc. Barracuda™ is a trademark of
Seagate Technology, Inc. Other product names are registered trademarks
or trademarks of their owners.

Seagate reserves the right to change, without notice, product offerings or
specifications. No part of this publication may be reproduced in any form
without written permission from Seagate Technology, Inc.

Revision status summary sheet

Sheets

Revision Date Writer/Engineer Affected

A (preliminary-01) 1/25/94 L. Newman/J. Olson All
A (preliminary-02) 2/15/94 L. Newman/J. Olson All
A 3/29/94 L. Newman/J. Olson All
B 10/3/95 L. Newman/J. Olson 8, 14, 15, 19, 24, 25,

26, 27, 29, 30, 32, 43,
44, 49, 51, 52, 53, 55,
60

Note. Product Manual 83328900 is Volume 1 of a two-volume

document with the SCSI interface information in the

SCSI-2 Interface Product Manual,

Part Number 77738479.

Volume 2

ST12450W/WD Product Manual, Rev. B v

Contents

1.0 Scope ................................................................................................................................. 1

2.0 Applicable standard and reference documentation ....................................................... 3

2.1 Standards ..................................................................................................................... 3

2.2 Applicable reference documents................................................................................... 3

3.0 General description........................................................................................................... 5

4.0 Standard features.............................................................................................................. 7

4.1 Performance ................................................................................................................. 7

4.1.1 Reliability............................................................................................................. 7

4.2 Unformatted and formatted capacities .......................................................................... 8

4.3 Options ......................................................................................................................... 8

4.4 Installation..................................................................................................................... 9

5.0 Performance characteristics ............................................................................................ 11

5.1 Internal drive characteristics ......................................................................................... 11

5.2 SCSI seek performance characteristics ........................................................................ 11

5.2.1 Seek time ............................................................................................................ 13

5.2.2 Format drive command execution time................................................................ 13

5.3 General performance characteristics ............................................................................ 14

5.4 Start/stop time............................................................................................................... 15

5.5 Prefetch/multi-segmented cache control ....................................................................... 15

5.5.1 Adaptive read lookahead..................................................................................... 16

5.6 Caching write data ........................................................................................................ 17

5.7 Synchronized spindle operation .................................................................................... 17

6.0 Reliability specifications................................................................................................... 21

6.1 Error rates..................................................................................................................... 21

6.1.1 Environmental interference.................................................................................. 21

6.1.2 Write errors ......................................................................................................... 21

6.1.3 Seek errors ......................................................................................................... 22

6.2 Reliability and service ................................................................................................... 22

6.2.1 Mean time between failures (MTBF).................................................................... 22

6.2.2 Air flow ................................................................................................................ 22

6.2.3 Preventive maintenance...................................................................................... 26

6.2.4 Service life........................................................................................................... 26

6.2.5 Service philosophy .............................................................................................. 26

6.2.6 Installation ........................................................................................................... 26

6.2.7 Service tools........................................................................................................ 26

6.2.8 Hot plugging Barracuda 2, 2HP disc drives ......................................................... 26

vi ST12450W/WD Product Manual, Rev. B

7.0 Physical/electrical specifications ................................................................................... 29

7.1 AC power requirements ............................................................................................ 29

7.2 DC power requirements ............................................................................................ 29

7.2.1 Conducted noise immunity ............................................................................ 30

7.2.2 Power sequencing ......................................................................................... 30

7.2.3 12V current profile ......................................................................................... 31

7.3 Heat/power dissipation.............................................................................................. 32

7.4 Environmental limits.................................................................................................. 32

7.4.1 Temperature.................................................................................................. 32

7.4.2 Relative humidity ........................................................................................... 32

7.4.3 Effective altitude (sea level) ........................................................................... 32

7.4.4 Shock and vibration ....................................................................................... 33

7.4.5 Air cleanliness ............................................................................................... 34

7.4.6 Acoustics ....................................................................................................... 34

7.5 Electromagnetic compatibility.................................................................................... 34

7.6 Mechanical specifications ......................................................................................... 35

7.6.1 Drive orientation ............................................................................................ 36

7.6.2 Cooling .......................................................................................................... 36

8.0 Media characteristics ...................................................................................................... 37

8.1 Media description...................................................................................................... 37

9.0 Defect and error management ........................................................................................ 39

9.1 Defects and errors .................................................................................................... 39

10.0 Option/configuration headers......................................................................................... 41

10.1 Drive ID/option select headers .................................................................................. 41

10.2 Synchronized spindles interface ............................................................................... 44

10.2.1 Electrical description...................................................................................... 44

10.3 Grounding ................................................................................................................. 45

11.0 Interface requirements .................................................................................................... 47

11.1 General description ................................................................................................... 47

11.2 SCSI interface messages supported......................................................................... 47

11.3 SCSI interface commands supported........................................................................ 48

11.3.1 Inquiry data.................................................................................................... 50

11.3.2 Mode sense data ........................................................................................... 50

11.4 SCSI bus conditions and miscellaneous features supported ..................................... 53

11.5 Synchronous data transfer ........................................................................................ 54

11.5.1 Synchronous data transfer periods supported .............................................. 54

11.5.2 REQ/ACK offset............................................................................................ 54

11.6 DC cable and connector ........................................................................................... 54

ST12450W/WD Product Manual, Rev. B vii

11.7 SCSI physical interface ............................................................................................. 55

11.7.1 Physical characteristics ................................................................................ 55

11.7.2 Connector requirements ............................................................................... 56

11.7.3 Electrical description ..................................................................................... 56

11.8 SCSI wide physical interface..................................................................................... 61

Index .......................................................................................................................................... 67

Figures

Figure 1. Barracuda 2, 2HP disc drive ...................................................................................... 1

Figure 2. Barracuda 2, 2HP disc drive (exploded view) ............................................................ 5

Figure 3. OEM interruptible thermal calibration implementation ................................................ 12

Figure 4. Synchronized drive interconnect diagram .................................................................. 17

Figure 5. Synchronized reference signal characteristics........................................................... 18

Figure 6. Air flow....................................................................................................................... 23

Figure 7. GYHX temperature measurement locations .............................................................. 24

Figure 8. RYGX temperature measurement locations .............................................................. 25

Figure 9. Temperature measurement location .......................................................................... 25

Figure 10. Typical Barracuda 2, 2HP drive +12V current profile ................................................. 31

Figure 11. Mounting configuration dimensions............................................................................ 35

Figure 12. Recommended mounting........................................................................................... 36

Figure 13. Barracuda 2, 2HP drive physical interface ................................................................. 41

Figure 14. Barracuda drive ID and option select headers ........................................................... 42

Figure 15. SCSI reference index signal driver/receiver combination........................................... 44

Figure 16. J5 configuration select header specification............................................................... 45

Figure 17. Barracuda 2, 2HP physical interface.......................................................................... 55

Figure 18. Single-ended transmitters and receivers.................................................................... 57

Figure 19. Typical differential I//O line transmitter/receiver and terminators................................ 59

Figure 20. Wide SCSI device connector ..................................................................................... 61

ST12450W/WD Product Manual, Rev. B 1

1.0 Scope

This manual describes Seagate Technol ogy®, Inc. Barracuda™ 2, 2HP
(2 head parallel) disc drives.

Barracuda drives support the Small Computer System Interface-2 (SCSI-

2) as described in the ANSI SCSI and SCSI-2 interface specifications to the
extent described in this manual. This manual defines the performance
characteristics of the Barracuda 2, 2HP drives. The

Pr oduct Manual

characteristics of this and other families of Seagate drives.

(part number 77738479) describes general SCSI interface

SCSI-2 Interface

Figure 1. Barracuda 2, 2HP disc drive

ST12450W/WD Product Manual, Rev. B 3

2.0 Applicable standard and
reference documentation

Seagate takes all reasonable steps to insure that its products are certifiable
to currently accepted standards. Typical applications of these disc drives
include customer packaging and subsystem design.

Safety agencies conditionally certify component parts, such as the Barra­cuda disc drive, based on their final acceptability in the end-use product. The
subsystem designer is responsible for meeting these conditions of accept­ability in obtaining safety/regulatory agency compliance in their end-use
product and certifying where required by law.

2.1 Standards

The Barracuda disc drive is a UL recognized component per UL1950, CSA
certified to CSA C22.2 No. 950-M89, and VDE certified to VDE 0805 and
EN60950.

The Barracuda disc drive is supplied as a component part. It is the respon­sibility of the subsystem designer to meet EMC/regulatory requirements.
Engineering test characterizations of radiated emissions are available from
the Seagate safety department.

2.2 Applicable reference documents

Barracuda 2, 2HP Installation Guide

Seagate part number: 83328890

SCSI-2 Interface Product Manual (volume 2)

Seagate part number: 77738479

ANSI small computer system interface (SCSI) documents

ANSI X3.131-1986 (SCSI-1)
X3T9.2/86-109 Rev. 10H (SCSI-2)
X3T9.2/91-010 Rev. 10 (SCSI-3) Parallel Interface

In case of conflict between this document and any referenced document, this
document takes precedence.

ST12450W/WD Product Manual, Rev. B 5

3.0 General description

Barracuda drives are low-cost, high-performance, random-access storage
devices designed to meet the needs of the original equipment manufacturer
(OEM) marketplace.

The Barracuda 2, 2HP drive has two read/write channels on the circuit board.
The SCSI-2 controller chip is modified to process data for two read/write
channels at once. This technology effectively doubles the internal data
transfer rate when compared to a conventional Barracuda 2 disc drive.

The Barracuda drive’s interface supports multiple initiators, disconnect/
reconnect, self-configuring host software, and automatic features that re­lieve the host from knowing the physical characteristics of the targets (logical
block addressing is used).

The head and disc assembly (HDA) is environmentally sealed at the factory.
Air circulates within the HDA through a non-replaceable filter to maintain a
contamination-free HDA environment.

Refer to Figure 2 for an exploded view of the drive. This exploded view is for
information only—never disassemble the HDA and do not attempt to service
items in the sealed enclosure (heads, media, actuator, etc.) as this requires
special facilities. The drive contains no replaceable parts. Opening the HDA
voids your warranty.

Figure 2. Barracuda 2, 2HP disc drive (exploded view)

6 ST12450W/WD Product Manual, Rev. B

Barracuda drives use a dedicated landing zone at the innermost radius of the
media to eliminate the possibility of destroying or degrading data by landing
in the data zone. The drive automatically goes to the landing zone when the
power is removed.

An automatic shipping lock prevents potential damage to the heads and
discs that results from movement during shipping and handling. The shipping
lock disengages when power is applied to the drive and the head load
process begins.

Barracuda drives decode track 0 location data from the dedicated servo
surface to eliminate mechanical transducer adjustments and relate d r eli­ability concerns.

A high-performance actuator assembly with a low-inertia, balanced, pat­ented, straight-arm design provides excellent performance with minimal
power dissipation.

ST12450W/WD Product Manual, Rev. B 7

4.0 Standard features

Barracuda 2, 2HP drives have the following standard features:

• 2 head parallel technology

• Integrated SCSI controller

• Single-ended or differential SCSI drivers and receivers

• Asynchronous and synchronous data-transfer protocols

• Firmware downloadable using a SCSI interface

• Selectable sector size from 180 to 4,096 bytes per sector

• Programmable sector-reallocation scheme

• Flawed sector reallocation at format time

• Programmable auto-write and auto-read reallocation

• Reallocation of defects on command (post format)

• 96-bit Reed-Solomon error-correction code

• Sealed head and disc assembly (HDA)

• No preventive maintenance or adjustments required

• Dedicated head-landing zone

• Automatic shipping lock

• Automatic thermal compensation

• Embedded Grey Code track address to eliminate seek errors

• Self-diagnostics performed at power-on

• 1:1 interleave

• Zone bit recording (ZBR)

• Vertical, horizontal, or top-down mounting

• Dynamic spindle brake

• Permanently mounted IC terminators (ST12450W models only)

• 1,024 Kbyte data buffer (see Section 5.5)

4.1 Performance

• Simultaneously processes data for two read/write channels (heads)

• Programmable multi-segmentable cache buffer

• 7,200 RPM spindle; average latency = 4.17 msec

• Command queuing of up to 64 commands

• Background processing of queue

• Supports start and stop commands

• Provides synchronized spindle capability

• Low audible noise for office environment

• Low power consumption

4.1.1 Reliability

• 500,000 hour MTBF

• Adaptive seek velocity; improved seek performance

• LSI circuitry

• Balanced low-mass rotary voice-coil actuator

8 ST12450W/WD Product Manual, Rev. B

4.2 Unformatted and Formatted Capacities

Standard OEM models are formatted to have 512-byte sectors.
ST12450 drives have nine (9) spare sectors per cylinder and one (1) spare

cylinder per unit.

Formatted Unformatted

1,849 Mbytes 2,437 Mbytes

Users having the necessar y equipment may modify t he data block size
before issuing a format command to obtain different formatted capacities.
User-available capacity also depends on the spare reallocation scheme
selected . See the Mode Sel ect command and the Fo rmat comm and in the

SCSI-2 Interface Product Manual

(part number 77738479).

4.3 Options

The capacity shown in Section 4.2 is normally provided. Other capacities
can be ord ered depend ing on the spar ing scheme an d sector size re­quested.

The following options are incorporated at the time of production or are
available separately.

• Front panel (green lens), part number 70869751
The standard front panel is black plastic. You may order other colors. Each

panel has a single rectangular green LED indicator lens that, when
glowing, indicates the drive is selected.

•

Barracuda 2, 2HP Installation Guide,

This manual provides basic information on the care and handling of
Winchester disc peripherals in general. Some drive installation informa­tion is included to assist those persons not familiar with the produc t. It
also includes basic information to assist in obtaining service for the drive.

• Single-unit shipping pack kit
The drive is shipped in bulk packaging to provide maximum protection

against transit damage. Units shipped individually require additional
prot ection as provided by the single-unit shi pping pack.

• Adapter accessory frame kit, part number 75790701
This kit contains the frame to allow a 3.5-inch drive to be mounted in

a 5.25-inch drive bay. It includes mounting hardware, front panel with a
green lens, an LED with cable that connects to the remote LED connector,
and installation instructions.

part number 83328890

ST12450W/WD Product Manual, Rev. B 9

4.4 Installation

For option jumper locations and definitions refer to Figure 14. Drive default
mode parameters are not normally needed for installation. Refer to
Section 11.3.2 for default mode parameters if you need them.

• Ensure that the SCSI ID of the drive is not the same as the host adapter.

• If multiple devices are on the bus, set the drive’s SCSI ID to one that is not
presently used by other devices on the bus.

• If the drive is the only device on the bus, attach it to the end of the SCSI bus
cable. Internal termination is available on single-ended (ST12450W)
drives by enabling this feature with a jumper (see Figure 14). External
terminators are required for differential (ST12450WD) drives. These
external terminators m ust be prov ided by the user , sy stems int egrator , or
host equipment manufacturer.

• If you attach the drive to a bus that contains other devices, and the new
drive is not attached to the end of the bus, remove termination from the new
drive.

• Set all approp riat e optio n jump ers prio r to ap plying po we r to th e driv e. If
you change j umpers after applying power, recycle the drive’s power to
make th e new settings eff ecti v e .

Formatting

• It is not necessary to low-level format this drive. The drive is shipped from
the factory low-level formatted in 512-byte sectors.

• Reformat the drive if:
a. You select a different sector size.

b. You select a different spare-sector allocation scheme.

ST12450W/WD Product Manual, Rev. B 11

5.0 Performance characteristics

This section provides performance-related characteristics and features of
Barracuda 2, 2HP drives.

5.1 Internal drive characteristics

Drive capacity, Mbytes unformatted 2,437
Read/write data heads, maximum (physical) 18
Read/write data heads, maximum (logical) 9
Bytes per track, average bytes 99,536
Bytes per surface, Mbytes unformatted 271.4
Cylinders/tracks per surface, user accessible 2,710
Tracks per inch 3,047
Bits per inch 52,187
Servo heads 1
Internal data rate per physical head, Mbits/sec, 34.3 to 56.5

variable with zone
Internal data rate per logical head, Mbits/sec, 68.6 to 113.0

variable with zone
Disc rotation speed 7,200 ± 0.5%
Average rotational latency, msec 4.17

5.2 SCSI seek performance characteristics

All performance charact eristics assume that automatic adaptive thermal
compensation is not in process when the drive receives the SCSI command.
Automatic adaptive thermal compensation will not interrupt an active SCSI
comma n d. If ad apt i ve ther mal c ompensa ti on i s in pr oce ss whe n a SCSI
command is received, the command is queued until the compensation for
the specific head bei ng compensated completes. When compensation
completes for the specific head being compensated, the first queued SCSI
command executes. When execution of the first queued command is
complete, the drive continues the compensation for the remaining head(s).

The above procedure continues until compensation for all heads has
completed, or until 10 mi nutes have elapsed. The drive initiates an auto­matic adaptive thermal compensation cycle once on power-up before
completing its initialization sequence and then once after 1 minute from the
end of initialization. After this, the drive initiates an automatic adaptive
thermal compensation cycle approximately once every 10 minutes. Non­interruptible automatic thermal compensation occurs at other times but
should be transparent to the user (e.g., during format, Re-zer o command,
at spindle-up, during read-error recovery, and during reassign-block func­tions) . You can use the R e-ze ro command t o r eset the t hermal compens a­tion timer back to its start so that the host knows when the interruption for
thermal compensation will occur.

12 ST12450W/WD Product Manual, Rev. B

Refer to Section 11.8 and to the

SCSI-2 Interface Product Manual

number 77738479) for additional timing details.

Start

A

Has

10 min.

No

timer

expired?

Set

10 minute

timer

Is

SCSI

command in

progress?

Complete
Command

Yes

Yes

No

All

heads

calibrated?

No

Select

next

head

No

Yes

received a SCSI

command?

calibrated?

TCAL

head

Has

target

All

heads

A

Yes

Yes

No

No

(part

Has

target

received a SCSI

command?

Yes

Target

completes

SCSI

command

Seek to

TCAL cyl
and select
next head

Seek to

TCAL cyl
and select
head zero

Figure 3. OEM interruptible thermal calibration implementation

ST12450W/WD Product Manual, Rev. B 13

5.2.1 Seek time

Drive level Drive including
Barracuda controller overhead
msec without disconnect

read write read write

Average typical* 8.0 9.0 9.0 10.0
Single track typical* 0.6 0.9 1.6 1.9
Full stroke typical* 17 19 18.0 20.0

*Typical seek values ar e measured under nominal condi tions o f temper a-

ture, voltage, and horizontal orientation on a representative sample of
drives.

5.2.2 Format drive command execution time

≥≥

for

≥ 512-byte sectors

≥≥

Maximum (with verify) 18 minutes
Maximum (without verify) 12 minutes

14 ST12450W/WD Product Manual, Rev. B

5.3 General performance characteristics

Minimum sector interleave 1 to 1
Data buffer to/from disc media (512-byte sector)

Data transfer rate (≤ 1 sector)
Minimum 8.56 Mbytes/sec*

Maximum 14.11 Mbytes/sec*
Data transfer rate (< 1 track)
Minimum 6.2 Mbytes/sec*

Maximum 10.3 Mbytes/sec*

SCSI interface data

Asynchronous transfer rate Asynchronous*
Maximum instantaneous 10.0 Mbytes/sec**

Sector sizes

Default 512-byte data blocks

Variable in even-sector sizes 180 to 4,096 bytes
Synchronous transfer rate, 2 bytes wide 5.0 to 20 Mbytes/sec
Read/write consecutive sectors on a track Yes
Flaw reallocation performance impact Negligible

(for flaws reallocated using the spare
sectors per track reallocation scheme)

Flaw reallocation performance impact Negligible
(for flaws reallocated using the spare
sectors per cylinder reallocation scheme)

Flaw reallocation performance impact 35 msec (typical)
(for flaws reallocated using the spare
tracks per volume reallocation scheme)

Overhead time for head switch 0.7 msec
Overhead time for one-track cylinder switch 1.6 msec (typical)
Average rotational latency 4.17 msec
* Rate measured from the start of the first sector transfer to or from the host.

**Assumes s ystem abi lity to support 5.0 Mbytes/s ec, 2 bytes wid e, and no

cable loss.

ST12450W/WD Product Manual, Rev. B 15

5.4 Start/stop time

Disabling the Motor Start option causes the drive to become ready within 30
seconds after DC power is applied at nominal voltage. This means the motor
starts as soon as power is applied. If a recoverable error condition is detected
during the start sequence, the drive will execute a recovery procedure and
may cause the time to become ready to exceed 30 seconds. During this time
the drive responds to some commands over the SCSI interface. Stop time is
less than 30 seconds (maximum) from removal of DC power.

Enabling the Motor Start option causes the internal controller to accept the
commands listed in the
than 3 seconds after applying DC power. After receiving the Motor Start
command, the drive becomes ready for normal operations within 30 seconds
(excluding error recovery procedure). The Motor Start command can also be
used to command the drive to stop the spindle (see the Start/Stop command
information in the

There is no power control switch on the drive.

SCSI-2 Interface Product Manual

SCSI-2 Interface Product Manual).

(77738479) less

5.5 Prefetch/multi-segmented cache control

The drive provides a prefetch/multi-segmented cache algorithm, which in
man y c ase s e nhan ces sys tem perf orma nce . T o sele ct th is f ea ture, the host
sends the Mode Select command with the proper values in the applicable
bytes in page 08h (see the
prefetch and cache operation enabled.

SCSI-2 Interface Product Manual).

Default is

Of the 1,024 Kbytes physical buffer space, approximately 960 Kbytes can be
used as a cache. The cache can be divided into logical segments from which
data is read and to which data is written.

The drive keeps track of the logical block addresses of the data stored in each
segment of the cache. If the cache is enabled (see RCD bit, Table 5.2.1-27
in the

SCSI-2 Interface Product Manual),

read command is retrieved from the cache before any disc access is initiated.
Data in contiguous logical blocks immediately beyond that requested by the
Read command can be retrieved and stored in the cache for immediate
transfer to the initiator on subsequent read commands. This is referred to as
the prefetch operation. Since data that is prefetched may replace data
already in the cache segment, an initiator can limit the amount of prefetch
data to optimize system performance. The drive never prefetches more
sectors than the number specified in bytes 8 and 9 of Mode page 08h (see
the

SCSI-2 Interface Product Manual).

Kbytes of the buffer are used as a circular buffer for read/writes, with no
prefetch operation and no segmented cache operation.

The following is a simplified description of the prefetch/cache operation:
Case A. A read command is received and the first logical block is already in

the cache.

1. The drive transfers to the initiator the first logical block requested plus all
subsequent contiguous logical blocks that are already in the cache. This
data may be in multiple segments.

data requested by the host with a

If the cache is not enabled, 960

16 ST12450W/WD Product Manual, Rev. B

2. When a re quest ed logica l block is rea ched that is not in an y s egment,
the d rive fetches i t and any r emaining re quested logi cal block a ddresses
from the d isc and p uts them in a se gment of the cache. The drive
transfers the remaining requested logical blocks from the cache t o the
initiator in accordance with the “buffer-full” ratio specification given in
Mode Select Disconnect/Reconnect parameters, page 02h (see the

SCSI-2 Int erfac e Pr o duct Man ual

3. The drive prefetches additional logical blocks contiguous to those
transferred in step 2 above and stores them in the segment. The drive
stops filling the segment when the maximum prefetch v alue has been
transferred (s ee the

Case B. A read command is received and the first logical block address
requested is not in any segment of the cache.

1. The drive fetches the requested logical blocks from the disc and
transfers them into a segment, then from there to the initiator in
accordance with the “buffer-full” ratio specification given in Mode Select
Disconnect/Reconnect parameters, page 02h (see the

face Pr oduct Manual

2. The drive prefetches additional logical blocks contiguous to those trans­ferred in Case A, step 2 above and stores them in the segment. The drive
stops filling the segment when the maximum prefetch value has been
transferred.

SCSI-2 Inter fac e Pr oduct Manual

).

).

).

SCSI-2 Inter-

During a prefetch, the drive crosses a cylinder boundary to fetch data only
if the Discontinuity (DISC ) bit is set to 1 in bit 4 of byte 2 of the Mode Select
parameters page 8h. Default is zero for bit 4 (see the

Pro duct Manual

Each cache segment is ac tually a self-c ontained circular buffer whose
length is an integer number of sectors. The wrap-around capability of the
individual segments greatly enhance s the cache’s overall performance,
allowing a wide range of user-selectable configurations including a pu re
prefetch strategy. The drive supports operation of any integer number of
segments from 1 to 1 6. Divide the 976, 896 bytes in the buffer by the number
of segments to get the segment size . Default is 3 segments. (See the

2 Interfac e Pr o duct Manual.

).

)

5.5.1 Adaptive read lookahead

Read lookahead causes the drive to continue reading data from the disc
following a normal read I/O until the read-ahead parameters are satisfied
(prefetch). If subsequent I/O requests can be satisfied from the prefetched
data in the data buffer, there is a significant improvement in performance
since a disc access is eliminated. If subsequent I/O requests cannot be
satisfied from the prefetched data, there is a reduction in performance due
to prefetch overhead.

The adaptive read lookahead feature suspends the prefetch operation if
three subsequent read I/O requests are not satisfied from the prefetched
data. This improves performance because unnecessary prefetches are
avoided.

SCSI-2 Interface

SCSI-

Prefetch is reinstated if an I/O request is sequential to a previous I/O request.

ST12450W/WD Product Manual, Rev. B 17

Master Sync

Source

Host

(or other drive)

Spindle
Control

Drive 1

+5V

R

T

J5

11
12

Spindle
Control

Drive 2

+5V

R

T

J5

11
12

Spindle
Control

Drive n

+5V

R

T

J5

11
12

Sync Interface

System

Interface

5.6 Caching write data

Write caching is a drive-write operation, which uses a drive’s buffer storage
area where data to be written to the disc is stored while the drive performs
the Write command.

Write caching is enabled along with read caching. Default is cache enabled.
For write caching, the same buffer space and segmentation is used as set
up for read functions. When a write command is issued, the cache is first
checked to see if any logical blocks to be written are already stored in the
cache from a previous read or write command. If there are, the respective
cache segments are cleared. The new data is cached for subsequent read
commands.

If a 10-byte CDB write command (2Ah) is issued with the data page out (DPO)
bit set to 1, no write data is cached, but the cache segments are still checked
and cleared, if needed, for any logical blocks that are being written (see the

SCSI-2 Interface Product Manual).

If the number of write data logical blocks exceeds the size of the segment
being written into when the end of the segment is reached, data is written into
the beginning of the same cache segment, overwriting data that was written
there at the beginning of the operation. However, the drive does not overwrite
data that has not yet been written to the disc.

5.7 Synchronized spindle operation

The synchronized spindle operation allows several drives operating from the
same host to operate their spindles at the same synchronized rotational rate.
Drives operating in a system in synchronized mode increase the system’s
capacity and transfer rate in a cost-effective manner.

The int erface consists of a twisted-pair cabl e, which connects the driv es in
the synchronized system in a daisy-chain configuration as shown in
Figure 4.

Figure 4. Synchronized drive interconnect diagram

18 ST12450W/WD Product Manual, Rev. B

The host can reconfigure the drive any time after power-up to be the master
or a slave by u sing the Mo de Sel ect c om mand on th e Rig id Disc Drive
Geometry page. The master provides the reference signal to which all other
drives phase-lock, including the master. There is only one master per
system, and th at c an be a d r ive or t he h ost co mp uter. All dr ives may be
configured as slaves allowing the host to provide the reference signal.

Each drive also can be configured for the non-synchronized mode in which
it ignores any referenc e sign al that m ig ht be present— th is is the default
mode as shipped from the factory. Connect the synchronized reference
signal to the host only if the host provides the reference signal. If the host
does not provide the reference signal, do not connect the host.

Rotational position locking
Note. Mode Select page 4, byte 17, bits 1 and 0.
RPL Description

00b Spindle synchronization is disabled (default value)
01b The target operates as a synchronized-spindle slave
10b The target operates as a synchronized-spindle master
11b The target operates as a synchronized-spindle master control

(not supported by the disc drive)

The VIC 2 LSI on the master drive provides the reference signal (SSREF +).
The index signal generates a 120 Hz signal. The signal is normally
false/negated (n ominal 0V) and makes a transition to the true/asserted
(nominal +5V) leve l to indicate the reference position during the revolution
period. Master and slave drives use the trailing (falling) edge of the
refere nce signal to phase lock their spindles. A maximum of 1 0 s econds is
allowed for a slave to synchronize with the reference signal. Figure 5 shows
the characteristics of the reference s ig nal.

T

1

SSREF +

Figure 5. Synchronized reference signal characteristics

0

1.0 µsec min.

1.37 µsec max.

T = 0.0083 seconds (± 1.0% max)

± 10 microseconds cycle-to-cycle variance
± 20 microseconds phase error while synchronized

ST12450W/WD Product Manual, Rev. B 19

SCSI interface factors

The Rotational Position Loc k i ng (RPL) field in byte 17 (bits 0 and 1) of the
Rigid Disc Drive Geometry mode par amete rs page (p age 04h) i s used for
enabling and disabling spindle synchronization m ode (see the

Interface Product Manual

creates a unit attention to all initiators. The sense key is set to Unit Attention
and the additional sense code is set to Spindles Synchronized (5C01).

After reaching synchronization, if the target detects a change of synchroni­zation and:

1. If the logical unit is not executing an I/O process for the initiator, then the
target creates a unit attention condition. The sense key is set to Unit
Attention and the additional sense code is set to Spindle Synchronized
(5C01) or Spindle Not Synchronized (5C02).

2. If the logical unit is executing an I/O process and no other error occurs,
then the target returns Check Condition status. The sense key is set to
Recovered Error if the target is able to complete the I/O process or to
Hardware Error if the target is unable to complete the I/O process. The
additional sense code is set to Spindle Synchronized (5C01) or Spindle
Not Synchronized (5C02).

You may operate the drive with a rotational skew when synchronized. The
rotational skew is applied in the retarded direction (lagging the synchronized­spindle master control). A rotational offset of up to 255/256 of a revolution
lagging may be selected. Select the amount of offset by using the Mode
Select command, Rigid Disc Drive Geometry page (page 04), byte 18 (see
the

SCSI-2 Interface Product Manual).

numerator of a fractional multiplier that has 256 as the denominator. For
example, 40h selects 40h/FFh or 1/4 of a revolution lagging skew, 80h
selects 1/2 of a revolution lagging skew, etc. Since the drive supports all
offset values from 0 to 255, values sent by the initiator are not rounded off.
The drive’s translation of the digital offset values to physical rotational offsets
results in offset values whose phase error lies within the ± 20 microseconds
phase error with respect to the supplied 120 Hz reference signal.

). When the target reaches synchronization, it

The value in byte 18 (0–FFh) is the

SCSI-2

The drive does not have the capability to adjust the rotational offset value
requested by the initiator to a physical offset in the drive that corresponds in
any way to sector boundaries or changes in ZBR zones. The initiator must
formulate these boundaries or changes, if required, to calculate the value of
offset it sends to the drive.

ST12450W/WD Product Manual, Rev. B 21

6.0 Reliability specifications

The following reliability specifications assume correct host and drive
interface, including all interface timings, power supply voltages, and
environmental requirements.

Seek error rate Less than 10 errors in 108 seeks
Recoverable error rate Less than 10 errors in 1011 bits transferred

(using default settings)
Unrecovered data Less than 1 sector in 1014 bits transferred
Miscorrected data Less than 1 sector in 1021 bits transferred
MTBF 500,000 hours
Service life 5 years
Preventive maintenance None required

6.1 Error rates

The error rates stated in this manual assume the following:

• The drive is operated per this manual using DC power as defined in

Section 7 .2.

• The drive has been formatted with the SCSI format commands.

• Errors caused by media defects or host system failures are excluded from

error rate computations. Refer to Section 9.0.

6.1.1 Environmental interference

When evaluating system operation under conditions of electromagnetic
interference (EMI), the performance of the drive within the system is
considered acceptable if the drive does not generate an unrecoverable
condition.

An unrecoverable error or condition is defined as one that:

• is not detected and corrected by the drive itself;

• is not capable of being detected from the error or fault status provided

through the drive or SCSI interface; or

• is not capable of being recovered by normal drive or system recovery

procedures without operator intervention.

6.1.2 Write errors

Write errors can occur as a result of media defects, environmental interfer­ence, or component malfunction. Therefore, write errors are not predictable
as a function of the number of bits passed.

If an unrecoverable write error occurs because of a component malfunction
in the drive, the error is classified as a failure affecting MTBF. Unrecoverable
write errors are those that cannot be corrected within two attempts at writing
the record with a read verify after each attempt (excluding media defects).

22 ST12450W/WD Product Manual, Rev. B

6.1.3 Seek errors

A seek error is defined as a failure of the drive to position the heads at the
addressed track. There must be no more than one recoverable seek error in
107 physical seek operations. After detecting an initial seek error, the drive
automatically reseeks to the addressed track up to three times. If a reseek
is successful, the extended sense report indicates a seek-positioning error
(15h), no-seek-complete error (02h), or track-follow error (09h), and the
sense key reports a recovered error (1h). If all three reseeks fail, a seek­positioning error (15h) is reported with a medium (3h) or hardware error (4h)
reported in the sense key. This is an unrecoverable seek error. Unrecover­able seek errors are classified as failures for MTBF calculations. Refer to
Section 5.1.1.2 of the

77738479).

SCSI-2 Interface Product Manual

(part number

6.2 Reliability and service

You can enhance the reliability of Barracuda 2, 2HP disc drives by ensuring
that the drive receives adequate cooling. This section provides recom­mended air-flow information, temperature measurements, and other infor­mation that may be used to enhance the service life of the drive.

6.2.1 Mean time between failures (MTBF)

The production disc drive achieves an MTBF of 500,000 hours when
operated in an average local disc drive ambient temperature of 95°F (35°C)
or less. Short-term excursions up to the specification limits (122°F, 50°C) of
the operating environment will not affect MTBF performance.

The following expression defines MTBF:

MTBF =

Estimated power-on operating hours means the estimated total power-on
hours for all drives in service.

Drive failure means any stoppage or substandard performance caused by
drive malfunction.

Data is calculated on a rolling-average base for a minimum period of six
months.

6.2.2 Air flow

The rack, cabinet, or drawer environment for the Barracuda 2, 2HP drive
must provide cooling of the electronics and head and disc assembly (HDA).
You should confirm that adequate cooling is provided using the temperature
measurement guidelines described below.

Orient the drive or direct air flow so that the least amount of air-flow resistance
is created while providing air flow to the electronics and HDA. Also, choose
the shortest possible path between the air inlet and exit to minimize the travel
length of air heated by the Barracuda 2, 2HP drive and other heat sources
within the rack, cabinet, or drawer environment.

Estimated power-on operating hours in the period

Number of drive failures in the period

Possible air-flow patterns are shown in Figure 6. Create the air-flow patterns
by using one or more fans, either forcing or drawing air as shown in the
illustrations. Other air-flow patterns are acceptable as long as the tempera­ture measurement guidelines are met.

ST12450W/WD Product Manual, Rev. B 23

Above unit

Note. Air flows in the direction shown (back to front)
or in reverse direction (front to back)

Note. Air flows in the direction shown or
in reverse direction (side to side)

Figure 6. Air flow (ST12450W shown)

Under unit

Above unit

Under unit

24 ST12450W/WD Product Manual, Rev. B

To confirm that required cooling for the Barracuda electronics and HDA is
provided, place the drive in its final mechanical configuration, perform
random write/read operations and, after the temperatures stabilize, measure
the case temperature of the components listed below.

Maximum allowable operating temperatures are listed in the last column.
Operation above these values may adversely affect the drive’s ability to meet
functional specifications.

Air-flow cooling
ST12450W
single-ended

MTBF

500k hours

Card Component Reference case temperature (°C)

GYHX Transmitter 1 64
GYHX Detector 2 73
GYHX VIC 2 3 59
GYHX Flash PROM 4 59
HDA housing Figure 9

The air-flow pattern with which the temperature guidelines above were
generated is shown in Figure 6. Local average air velocities were 0.61 msec
(120 lfpm) and inlet air temperature to the drive was 30°C (86°F).

The maximum allowable HDA case temperature is 60°C.

2

1

Figure 7. GYHX temperature measurement locations

34

ST12450W/WD Product Manual, Rev. B 25

Air-flow cooling
ST12450WD
differential

MTBF

500k hours

Card Component Reference case temperature (°C)

RYGX Transmitter 1 64
RYGX Detector 2 73
RYGX VIC 2 3 59
RYGX Flash PROM 4 59
HDA housing Figure 9

The air-flow pattern with which the temperature guidelines above were
generated is shown in Figure 6. Local average air velocities were 0.61
msec (120 lfpm) and inlet air temperature to the drive was 30°C (86°F).

The maximum allowable HDA case temperature is 60°C.

2

1

Figure 8. RYGX temperature measurement locations

34

Measure the HDA housing temperature at the location specified in Figure 9.

1.00

Figure 9. Temperature measurement location

.50

26 ST12450W/WD Product Manual, Rev. B

6.2.3 Preventive maintenance

No preventive maintenance is required.

6.2.4 Service life

The drive has a useful service life of five years. Depot repair or replacement
of major parts is permitted during this period.

6.2.5 Service philosophy

Spec ial equ ipm ent is re quired to repair the d rive’s H DA. To achieve the
5-year service life, repairs must be performed only at a properly equipped
and staffed s ervice and repair facility. T r ou bleshooti ng and repai r of PCB s
in the field is not recommended because of the extensive diagnostic
equipment req uir ed for ef fective s ervicing. A lso, the re are no spare parts
available for this drive. T he drive’ s warranty is voided if the HDA is opened.

6.2.6 Installation

The drive is designed, manufactured, and tested with a “plug in and play”
installation philosophy. This philosophy minimizes the requirements for
highly trained personnel to integrate the drive into the OEM’s system,
whether in a factory or field environment. Refer to the

Installation Guide

(83328890) for installation instructions.

Barracuda 2, 2HP

The drive has been low-level formatted at the factory and does not need to
be reformatted.

6.2.7 Service tools

No special tools are required for site installation or recommended for site
maintenance. Refer to Section 6.2.3. The depot repair philosophy of the drive
precludes the necessity for special tools. Field repair of the drive is not
practical because users cannot purchase individual parts for the drive.

6.2.8 Hot plugging Barracuda 2, 2HP disc drives

Caution. Hot-plug drives are not designed for simultaneous power discon-

nection and physical removal.

During power-up and power-down periods, the hot SCSI connect/disconnect
capability does not produce glitches or any corruptions on an active SCSI
bus. Barracuda 2, 2HP drives conform to the SCSI-3 standard requirements
for glitch-free power-on and power-off. The drive maintains the high-imped­ance state of the device connector contacts during a power cycle until the
transceiver is enabled.

Note. The systems integrator must ensure that no temperature, energy, or

voltage hazard is presented during the hot connect/disconnect opera­tion.

Procedure:

1. Configure the drive with no connection between the drive and the
TRMPWR signal on the SCSI bus. To accomplish this, remove all
jumpers from connector J1.

ST12450W/WD Product Manual, Rev. B 27

2. Ensure that all SCSI devices on the bus have receivers that conform to
the SCSI-3 standard.

3. Eliminate all I/O processes for the drive.

4. Wait until the drive motor and discs have come to a complete stop prior
to changing the plane of operation, ensuring data integrity.

5. Insert or remove the drive after meeting the following conditions:

Caution. Do not hot-plug the first or last device on the SCSI bus (the

SCSI bus termination must be external to the drive you are
inserting or removing).

a. If you are inserting the drive, connect its power ground and logic

ground at least 1 millisecond before coming into contact with the bus
connector. Maintain these ground connections during and after con­necting the device to the bus.

b. If you are removing the device, maintain its power ground and logic

ground connection for at least 1 millisecond after disconnecting the
device from the bus.

c. You may simultaneously switch the power to the electronics and

mechanics of the drive with the bus contacts, if the power distribution
system is able to maintain adequate power stability to other devices
during the transition and if you have met the grounding requirements
given in steps 5a and 5b.

d. Ensure that the drive carrier discharges all static electricity prior to

inserting the drive into the system.

Note. Do not remove or add terminator power or resistance to the SCSI bus

while hot plugging a disc drive.

ST12450W/WD Product Manual, Rev. B 29

7.0 Physical/electrical specifications

This section provides information relat ing to the physical and electrical
characteristics of Barracuda 2, 2HP drives.

7.1 AC power requirements

None.

7.2 DC power requirements

The voltage and current requirements for a single drive are shown below.
Value s indicated apply at the drive ’s power connector.

Table 1. DC power requirements

ST12450W ST12450WD

[8]

Voltage 5V
regulation

Max operating current DC 3σ [1] 1.32a 0.91a 1.65A 0.91A
Max start current

(peak) DC 3σ [3] [6] 1.3A 2.18A 1.43A 2.18A

(peak) AC 3σ [3] — 3.1A — 3.1A
Delay motor start (max) DC 3σ [1] [4] 1.25A 1.5A 1.31A 1.5A
Peak operating current

Typical DC X [1] [7] 1.3A 0.84A 1.6A 0.84A

Maximum DC 3σ [1] 1.32A 0.91A 1.65A 0.91A

Maximum (peak) AC 3σ 1.4A 1.85A 2.4A 1.85A
Track following at

OD DC X [1] 1.3A 0.78A 1.4A 1.85A

ID DC X [1] 1.3A 0.82A 1.4A 0.78A
Read track

OD DC 3σ [1] [11] 1.4A 0.81A 1.9A 0.81A

AC 3σ 1.5A 1.16A 2.5A 1.16A
Seeking

Typical DC X [1] [10] 1.3A 1.06A 1.4A 1.06A

Maximum DC 3σ [1] 1.3A 1.14A 1.44A 1.14A

Maximum (peak) AC 3σ 1.3A 1.85A 2.2A 1.85A

[5]

Notes

±±

±5%

±±

12V 5V

[2]

±±

±5%

±±

±±

±5%

±±

[8]

12V

±±

±5%

±±

[2]

Notes:

[1] Measured with average reading DC ammeter . Instantaneous +1 2V cur rent

peaks will exceed these values.

[2] A – 1 0% tolerance i s permissible during initial start of the spindle a nd must

return to ±5% be fore 7,200 RPM is reached. The ±5% must be maintained
after the drive signals that its power- up sequence has been completed

and that it can accept selection by the host initiator.
[3] See Figure 10.
[4] This condition occurs when the Motor Start Option is enabled and the

drive has not yet received a Start Motor command.
[5] See Section 7.2.1 “Conducted noise immunity.” Specified voltage to ler-

ance includes ripple, noise, and transient response.

continued

30 ST12450W/WD Product Manual, Rev. B

continued from previous page

[6] At 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.

[7] Operating condition is defined as a third-stroke seek at OD and read

one track. A command is issued every 0.07 sec. (differential); 0.075

sec. (single-ended).
[8] No terminator power. See Section 11.7.3.4.
[9] All power-saving features enabled.
[10] Seeking is defined as a third-stroke seek at OD. A command is issued

every 20 msec.
[11] Read track is defined as repeat reads of track 15 with a 60% duty cycle.

Notes:

1. Minimum current loading for each supply voltage is not less than 3%
of the maximum operating current shown.

2. The +5V and +12V supplies employ separate ground returns.

3. Where power is provided to multiple drives from a common supply,
careful consideration for individual drive power requirements should
be noted. Where multiple units are powered on simultaneously, the
peak starting current must be available to each device.

7.2.1 Conducted noise immunity

Noise is specified as a periodic and random distribution of frequencies
covering a band from DC to 10 MHz. Maximum allowed noise values given
below are peak-to-peak measurements and apply at the drive’s power
connector.

0 to 100 kHZ 100 kHz to 10 MHz

++

+5V 150 mV 100 mV

++
++

+12V 150 mV 100 mV

++

7.2.2 Power sequencing

The drive does not require power sequencing. The drive protects against
inadvertent writing during power-up and down. Daisy-chain operation re­quires that power be maintained on the terminated device to ensure proper
termination of the peripheral I/O cables.

To automatically delay motor start based on the target ID (SCSI ID), select
the Delay Motor Start option and deselect the Enable Motor Start option on
the J4 connector. See Section 10.1 for pin selection information.

To delay the motor until the drive receives a Start Unit command, select the
Enable Motor Start option on the J4 connector.

ST12450W/WD Product Manual, Rev. B 31

7.2.3 12V current profile

Figure 10 identifies the drive’s +12V current profile. The current during the
various times is as shown.

3.0

2.85

2.5

2.0

1.9

1.5

+12V CURRENT (A)

1.0

0.5

T0

0.0

Peak AC

Nominal (average) curve

Minimum AC

T2

T1

0 5 10 15 20 25 30

Figure 10. Typical Barracuda 2, 2HP drive

T3

T5

T4

TIME (S)

T6

++

+12V current profile

++

T7

T0 Power is applied to the drive.
T1 Controller self-tests are performed.
T2 The spindle begins to accelerate under current limiting after performing

internal diagnostics. See Note 1 of Table 1.
T3 The spindle is up to speed and the head-arm restraint is unlocked.
T4 Heads move from the landing zone to the data area.
T5 The adaptive calibration sequence is performed.
T6 Thermal calibration.
T7 Calibration is complete and the drive is ready for reading and writing.

Note. All times and currents are typical. See Table 1 for maximum current

requirements.

32 ST12450W/WD Product Manual, Rev. B

7.3 Heat/power dissipation

The heat and power dissipation values for your drive are listed below.

ST12450W ST12450WD

Typical seek and read 16W 18W
power dissipation of DC power (54 BTUs/hr) (62 BTUs/hr)
average at nominal voltages

Typical power dissipation 15W 16W
under track following conditions (51 BTUs/hr) (54 BTUs/hr)

7.4 Environmental limits

Temperature and humidity must not cause condensation within the drive.
Altitude and atmospheric pressure specifications are referenced to a stan­dard day at 58.7°F (14.8°C). Maximum wet bulb temperature is 82°F (28°C).

7.4.1 Temperature

a. Operating

The MTBF specification for the drive is based on operating at a local
ambient temperature of 95°F (35°C). Occasional excursions to drive
ambient temperatures of 122°F (50°C) may occur without impact to
specified MTBF. The enclosure for the drive should be designed such that
the temperatures at the locations specified in Figures 7 and 8 are not
exceeded. Air flow may be needed to achieve these temperatures.
Continual or sustained operation at case temperatures above these
values may degrade MTBF.

The d rive mee ts all specifications within a 4 1 ° to 1 22 °F ( 5° to 50°C) drive
ambient temperature range with a maximum gradient of 36°F (20°C) per
hour.

b. Non-operating

Non-operating temperatur e should r emain betw een –40° to 1 5 8° F (– 40°
to 70°C) package ambient with a maximum gradient of 36°F (20 °C)
per hour. This assumes that the drive is packaged in the shipping
container designed by Seagate.

7.4.2 Relative humidity

The values below assume that no condensation on the drive occurs.
a. Operating

5% to 95% relative humidity with a maximum gradient of 10% per hour

b. Non-operating

5% to 95% relative humidity

7.4.3 Effective altitude (sea level)

a. Operating

–1,000 to +10,000 feet (–305 to +3,048 meters)

b. Non-operating

–1,000 to +40,000 feet (–305 to + 12,210 meters)

ST12450W/WD Product Manual, Rev. B 33

7.4.4 Shock and vibration

Shock and vibrati on limits are measured directly on the drive’s chassis.
Ensure that you use an enclosure that buffers and restri cts the drive’s
movements to meet the shock and vibra tion requirements listed below.

The limits of shock and vibration defined within this manual a r e s pecified
with the drive mounted in one of the two met ho ds shown in Figure 12.

7.4.4.1 Shock

a. Operating in a normal environment

The drive as installed for normal operation operates error free while
subjected to intermittent shock not exceeding:

2.0 Gs at a maximum duration of 11 msec (half-sinewave)

Shock may be applied in the X, Y, or Z axis.

b. Operating in an abnormal environment

The drive as installed for normal operation does not incur physical
damage while subjected to intermittent shock not exceeding:

10 Gs at a maximum duration of 11 msec (half-sinewave)

Shock occurring at abnormal levels may degrade operating performance
during the abnormal shock period. Specified operating performance
continues when normal operating shock levels resume.

Shock may be applied in the X, Y, or Z axis. Shock is not to be repeated
more than two times per second.

c. Non-operating

The limits of non-operating shock apply to all conditions of handling and
transportation. This includes both isolated drives and integrated drives.

The drive does not cause drive damage or performance degradation
while subjected to non-repetitive shock not exceeding:

50 Gs at a maximum duration of 11 msec (half-sinewave)

Shock may be applied in the X, Y, or Z axis.

d. Packaged

The drive as packaged by Seagate for general freight shipment with ­stands a drop test against a concrete floor or equivalent with specifica­tions n ot e x ce e ding :

20 pounds (8.95 kg) for pack’s gross weight
42 inches (1,070 mm) for distance dropped

Drop test applies to a single or multiple drive pack.

34 ST12450W/WD Product Manual, Rev. B

7.4.4.2 Vibration

a. Operating in a normal environment

The drive as installed for normal operation operates error free while
subjected to continuous vibration not exceeding:

5-400 Hz @ 0.5 G

Vibration may be applied in the X, Y, or Z axis.

b. Operating in an abnormal environment

Equipment as installed for normal operation does not incur physical
damage while subjected to periodic vibration not exceeding:

15 minutes of duration at major resonant frequency
5-400 Hz @ 0.75 G

Vibration occurring at these levels may degrade operating performance
during the abnormal vibration period. Specified operating performance
continues when normal operating vibration levels are resumed—this
assumes system recovery routines are available.

Abnormal vibration may be applied in the X, Y or Z axis.

c. Non-operating

The limits of non-operating vibration apply to all conditions of handling
and transportation. This includes both isolated drives and integrated
drives.

The drive does not incur physical damage or degraded performance as
a result of continuous vibration not exceeding:

5-22 Hz @ 0.040 inches (1.02 mm) displacement
22-400 Hz @ 2.00 Gs

Vibration may be applied in the X, Y, or Z axis.

7.4.5 Air cleanliness

The drive is designed to operate in a typical office environment with minimal
environmental control.

7.4.6 Acoustics

Sound power during idle mode (when the drive is not seeking, reading, or
writing) is 4.7 bels typical when measured to ISO 7779 specifications.

7.5 Electromagnetic compatibility

As a component assembly, the drive is n ot r equired to meet any susceptibil­ity performa nce requirements. The system integrator is responsible for
performing tests to ensure th at equi pment operating in the same system as
the drive does not adversely affect t he performance of t he d rive. See
Table 1 a nd Section 7 .2 “D C p ow er r e quirements.”

ST12450W/WD Product Manual, Rev. B 35

7.6 Mechanical specifications

The following nominal dimensions do not include the decorative front-panel
accessory. Refer to Figure 11 for detailed mounting configuration dimen­sions.

Height 1.63 in 41.4 mm
Width 4.00 in 101.6 mm
Depth 5.97 in 151.6 mm
Weight 2.3 lb 1.04 kg

T
U

[1]

R

F

[2]

G

W

J

[4]

ED

K

L

A

M

Notes:



[1]

Mounting holes two on each



side, 6-32 UNC. Max screw



length into side of drive is 



0.15 in. (3.81 mm).





[2]

Mounting holes five on



B

Z

H

S

V

bottom, 6-32 UNC. Max 



screw length into bottom of



drive is 0.15 in. (3.81 mm).





[3]

Power and interface



connections.





[4]

Decorative front panel.

Inches Millimeters

±

5.740

A

±

4.000

B

±

1.620

C

±

.615

D

±

4.000

E

±

.250

F

±

1.750

G

±

3.750

H

±

2.370

J

±

5.420

K

±

5.565

L

±

5.968

M

±

.190

N

±

.347

P

±

1.725

R

±

4.100

S

±

.190

T

max

0.015

U

±

0.265

V

±

2.145

W

±

1.755

Z

0.010

0.010

0.034

0.020

0.005

0.005

0.010

0.010

0.010

0.020

0.010

0.035

0.015

0.015

0.010

0.010

0.010

0.020

0.010

0.010

[3]

N



C

P

145.80 

101.60 

41.14 

15.68 

101.60 

6.35 

44.45 

95.25 

60.20 

137.69 

141.35 

151.58 

4.826 

8.81 

43.82 

104.14 

4.83 

0.381 

8.50 

54.48 

44.58

±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±

max

±
±
±

.25
.25
.86
.50
.13
.13
.25
.25
.25
.50
.25
.90
.38
.38
.25
.25
.25


.50
.25
.25

Figure 11. Mounting configuration dimensions

36 ST12450W/WD Product Manual, Rev. B

7.6.1 Drive orientation

The balanced rotary arm actuator design of the drive allows it to be mounted
in any orientation. All drive performance evaluations, however, have been
done with the drive in horizontal (discs level) and vertical (drive on its side)
orientations, which are the two preferred mounting orientations.

Figure 12. Recommended mounting

7.6.2 Cooling

Ensure that the enclosure you use provides adequate cooling so that th e
ambient temperature immediately surrounding the drive does not e xceed
tempe ratur e condition s specif ied in Section 7.4. 1 . E nsure th at y ou pro vide
adequa te air circul ation around the printed circuit boards (PCBs) to meet
the requirements of Section 6 .2 .2.

ST12450W/WD Product Manual, Rev. B 37

8.0 Media characteristics

This section provides information regarding the media used in Barracuda 2,
2HP disc drives.

8.1 Media description

The media used on the drive has a diameter of approximately 95 mm (3.7
inches). The aluminum substrate is coated with a thin-film magnetic material,
which has a proprietary protective layer for improved durability and environ­mental protection.

ST12450W/WD Product Manual, Rev. B 39

9.0 Defect and error management

The drive, as delivered, complies with this product manual. The read error
rates and specified storage capacities are not dependent on using defect­management routines by the host (initiator).

Defect and error management in the SCSI system involves the drive’s
internal defect/error management and SCSI system error considerations
(errors in communications between the initiator and the drive). Tools for
designing a defect/error management plan are briefly outlined in this section.
References to other sections are provided when necessary.

9.1 Defects and errors

Identified defects are recorded on the drive’s defects list (referred to as the
primary or ETF defect list). These known defects are reallocated during the
initial drive format at the factory. (See Format Unit command Section 5.2.1.2
in the

SCSI-2 Interface Product Manual,

correction by ECC recovers data from additional flaws if they occur.
Details of the SCSI commands supported by the drive are described in the

SCSI-2 Interface Product Manual.

Error Recovery philosophy is presented in Section 6 of the

Product Manual.

Also, more information about the drive’s

part number 77738479.) Data

SCSI-2 Interface

ST12450W/WD Product Manual, Rev. B 41

SCSI I/O

Connector

DC Power
Connector

J4

J01

J5

10.0 Option/configuration headers

This section describes ho w to configure Barracuda 2, 2HP drives using the
option headers on the drives. These option headers may be used to
customiz e many functions of the drives for your particular system.

10.1 Drive ID/option select headers

The headers desc ribed in this section enable you to configure the drive to
meet specific functionality requirements.

Figure 13. Barracuda 2, 2HP drive physical interface

42 ST12450W/WD Product Manual, Rev. B

Figure 14 illustrates the drive’s ID and option select jumper connectors.

SCSI ID = 0
SCSI ID = 1
SCSI ID = 2
SCSI ID = 3
SCSI ID = 4
SCSI ID = 5
SCSI ID = 6
SCSI ID = 7
SCSI ID = 8
SCSI ID = 9
SCSI ID = 10
SCSI ID = 11
SCSI ID = 12
SCSI ID = 13
SCSI ID = 14
SCSI ID = 15
Remote LED Connector

Spindle Sync
Cable Connector

SSREF

J5

Pin 1

Connector

J5

Power

Connector

SCSI

Pin 1

Pin 1

Pin 1

J4

Pin 1

Pin 1

J01

J4

Reserved
Enable Drive Terminators*
Parity Disable
Enable Motor Start
Delay Motor Start
Write Protect

Pin 1

Term. Power from Drive

*

Term. Power from SCSI Bus

*

Term. Power to SCSI Bus
Term. Power to SCSI Bus and Drive

*

* Valid for single ended drives only.

Figure 14. Barracuda drive ID and option select headers

Pin 3

J01

Pin 1
Pin 2

ST12450W/WD Product Manual, Rev. B 43

Block Pins Function

J01 1 & 2* Terminator power supplied by the drive.

2 & 4* Terminator power supplied from the SCSI bus.
1 & 3 Terminator power supplied to the SCSI bus.
1 & 3 and Terminator power supplied to the SCSI bus and

2 & 4* drive.

J4 1 & 2 Write Protect option. Jumper installed protects the entire

disc drive. Default is no jumper.

3 & 4 Delay Motor Start option. Jumper installed waits for ten

(10) seconds for each target ID number plus a maximum
power-up delay of 3 seconds before starting the spindle
motor automatically. Default is no jumper.

Example:

If target ID is equal to two (2)

(2 x 10) + 3 = 23

Target spindle motor starts
in twenty-three (23) seconds.

5 & 6 Enable Motor Start option. Jumper installed causes the

target to wait for the Start Unit command from the SCSI
host. No jumper installed causes the unit to look at the
Delay Motor Start jumper. Default is no jumper.

7 & 8 Parity Disable option. Jumper installed causes parity

checking and error reporting to be disabled. Default is no

jumper.
9 & 10 Reserved. Default is no jumper.
11 & 12* Enable Single-Ended Drive Terminator. Jumper installed

enables the drive terminator. Jumper removed disables

the drive terminator. Default is no jumper.
13 & 14 Reserved. Default is no jumper.
15 & 16 Reserved. Default is no jumper.

J5 1 & 2** SCSI Target ID 0

3 & 4** SCSI Target ID 1
5 & 6** SCSI Target ID 2
7 & 8** SCSI Target ID 3
9 & 10 Remote LED connector. Pin 9 is cathode (neg), Pin 10 is

anode (pos). Pin 10 is current limited through a 1K ohm,

1/10W resistor.
11 & 12 Spindle sync cable connector. Pin 11 is the SSREF+ or

reference index signal. Pin 12 is Gnd.

* Valid for single-ended (ST12450W) drives only.
**See Figure 14 to set the SCSI ID.

44 ST12450W/WD Product Manual, Rev. B

10.2 Synchronized spindles interface

The synchronized spindles interface (SSI) allows several drives operating
from the same host to operate their spindles at a synchronized rotational rate.
Details of the electrical and physical interfaces follow in Sections 10.2.1,

10.2.1.2, and 10.2.1.3. The system operation is described in Section 5.7.

10.2.1 Electrical description

The electrical interface consists of one digital TTL reference index signal and
ground. The reference index signal (SSREF+) is an output if the drive is
configured as a master and is an input otherwise. The reference index signal
is connected from drive to drive in a daisy-chain fashion as shown in Figure 4.

10.2.1.1 Drivers and receivers

Figure 15 shows a diagram of the driver/receiver circuit. The ST12450W/WD
use J5 pins 11 and 12 for spindle sync reference. The driver circuits have the
following electrical specifications:

Negated (false): 0.V to +0.4V @ I = –24 mA (max)
Asserted (true): +2.24V to +5.25V @ I = +250 µA

Main PWA

Driver Receiver

2.21K Ohm

+5V

Figure 15. SCSI reference index signal driver/receiver combination

SSREF +

GND

Open

Collector

J5 - 11

J5 - 12

ST12450W/WD Product Manual, Rev. B 45

10.2.1.2 Termination

The reference index signal (SSREF+) is terminated with a 2.21K ohm
resistor. Each single-ended drive has a terminator resistor located on the
main PCB. The terminator resistor is not removable and is always in the
circuit; however, you can disable termination by using a jumper option. See
Section 10.1. There is no provision for internal termination on differential
models. See Section 11.7.3.2. A diode prevents current from backfeeding.

10.2.1.3 Physical interface

The dimensions of the J5 connector mounted on the main PCB to intercon­nect the drives are shown in Figure 16. It is a 12-pin, 6-position gold 2 mm
header type connector. Only pins 11 and 12 are used for connecting the
reference index signal cable, as shown in Figure 14. Pin 11 is SSREF+ and
pin 12 is ground.

.520

.079

(2 mm)

(13.2 mm)

Pin 1

Figure 16. J5 configuration select header specification

10.3 Grounding

Signal ground (PCB) and HDA ground are connected together in the
Barracuda 2, 2HP family drives—do not separate this connection. Maximiz­ing the conductive contact area between HDA ground and system ground
may reduce radiated emissions. A bracket shield with tapped holes is
available to system integrators. This shield makes it easier to attach a braid
or similar high-frequency grounding device. If you do not want the system
chassis to be connected to the HDA/PCB ground, you must provide a
nonconductive (electrically isolating) method of mounting the drive in the
host equipment; however, this may increase radiated emissions and is the
system designer’s responsibility.

.079

(2 mm)

J5

.185

(4.7 mm)

ST12450W/WD Product Manual, Rev. B 47

11.0 Interface requirements

This section describes the Barracuda 2, 2HP interface requirements.

11.1 General description

The major portion of the interface requirements/implementation is de­scribed in the

11.2 SCSI interface messages supported

Table 2 lists the messages supported by the Barracuda SCSI-1 and
SCSI-2 modes.

Table 2. SCSI messages supported
Msg Supported by:

code SCSI-1 SCSI-2 Message name

01h*** Y Y Extended messages
06h Y Y Abort
0Dh Y Y Abort tag
0Ch Y Y Bus device reset
0Eh N Y Clear queue
00h Y Y Command complete
04h Y Y Disconnect
80h-FFh Y Y Identify
23h N N Ignore wide residue (two bytes)
0Fh N N Initiate recovery
05h Y Y Initiator detected error
0Ah Y Y Linked command complete
0Bh Y Y Linked command complete with flag
09h Y Y Message parity error
07h Y Y Message reject
*** N N Modify data pointer
08h Y Y No operation

21h N Y Head of queue tag
22h N Y Ordered queue tag
20h N Y Simple queue tag
10h N N Release recovery
03h Y Y Restore pointers
02h Y Y Save data pointer
*** Y Y Synchronous data transfer request
11h N N Terminate I/O process
12h N N Continue I/O Process
13h N N Target transfer disable
*** N Y Wide data transfer request

SCSI-2 Inter face Product Manual

Queue tag messages (two bytes)

(part number 77738479).

*** Extended messages (see the

SCSI-2 Interface Product Manual)

48 ST12450W/WD Product Manual, Rev. B

11.3 SCSI interface commands supported

Table 3 lists the SCSI interface commands supported in SCSI-1 and
SCSI-2 modes. Barracuda 2, 2HP family drives can be changed back and
forth between SCSI-1 and SCSI-2 modes us ing the Change Definition
command. Standard OEM drives are shipped set to operate in SCSI-2
mode.

Table 3. Supported commands
Command Supported by:

code SCSI-1 SCSI-2 Command name

00h Y Y Test Unit Ready
01h Y Y Rezero Unit
03h Y Y Request Sense

Y Y Extended Sense
Y Y Field Pointer Bytes

N N Actual Retry Count Bytes
04h Y Y Format Unit [1]
07h Y Y Reassign Blocks
08h Y Y Read
0Ah Y Y Write
0Bh Y Y Seek
12h Y Y Inquiry

N Y Vital Product Data Page

N Y Unit Serial Number Page

N Y Implemented Operating Def. Page

N Y Firmware Numbers Page

N Y Date Code Page

N Y Jumper Settings Page
15h Y Y Mode Select

(same pages as Mode Sense
command shown below)

16h Y Y Reserve

Y Y 3rd Party Reserve

N N Extent Reservation
17h Y Y Release
18h N N Copy
1Ah Y Y Mode Sense

Y Y Unit Attention Page (00h)

Y Y Error Recovery Page (01h)

Y Y Disconnect/Reconnect Control (page 02h)

Y Y Format Page (03h)

Y Y Rigid Disc Drive Geometry Page (04h)

N Y Verify Error Recovery Page (07h)

N Y Caching Parameters Page (08h)

N Y Control Mode Page (0Ah)

N Y Notch and Partition Page (0C)

(media zones)

1Bh Y Y Start Unit/Stop Unit

continued

ST12450W/WD Product Manual, Rev. B 49

continued from previous page

Command Supported by:
code SCSI-1 SCSI-2 Command name

1Ch Y Y Receive Diagnostic Results

Y Y Supported Diagnostics Pages
Y Y Translate Page

1Dh Y Y Send Diagnostics Page

Y Y Supported Diagnostics Pages

Y Y Translate Page
25h Y Y Read Capacity
28h Y Y Read Extended
2Ah Y Y Write Extended
2Bh Y Y Seek Extended
2Eh Y Y Write and Verify
2Fh Y Y Verify
30h N N Search Data High
31h N N Search Data Equal
32h N N Search Data Low
33h N N Set Limits
34h N N Prefetch
35h N Y Synchronize Cache
36h N N Lock-Unlock-Cache
37h Y Y Read Defect Data
39h N N Compare
3Ah N N Copy and Verify
3Bh Y Y Write Buffer [2]
3Ch Y Y Read Buffer [2]
3Eh Y Y Read Long
3Fh Y Y Write Long
40h Y Y Change Definition
41h N N Write Same
42-4Bh N N Not used
4Ch N N Log Select
4Dh N N Log Sense
4E-54 N N Not used
55h N Y Mode Select (10)
56h N Y Reserve (10)
57h N Y Reserve (10)
58-59 N N Not used
5Ah N Y Mode Sense (10)
5B-5F N N Not used
60-BFh N N Not used
C0-DFh N N Not used
EO-FFh N N Not used

[1] Format to any even number of bytes per sector from 180 to 4,096.
[2] If cache is enabled (RCD = 0 in Mode Sense page 08h), byte transfer

length is 976,896 bytes plus a 4-byte header.
If cache is disabled (RCD = 1), byte transfer length is 976,896 bytes plus

a 4-byte header.

50 ST12450W/WD Product Manual, Rev. B

11.3.1 Inquiry data

Table 4 lists the Inquiry command data that the drive should return to the
initiator per the format provided in the

Table 4. Barracuda 2, 2HP family drive inquiry data

Bytes Data (hex)

0-15 00 00 ** *** 8F 00 00 3A 53 45 41 47 41 54 45 20 Vendor ID
16-31 53 54 [31 32 34 35 30 57] 20 20 20 20 20 20 20 20 Product ID
32-47 R# R# R# R# S# S# S# S# S# S # S# S# 00 00 00 00
48-63 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
64-79 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
80-95 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

96-111 00 43 6F 70 79 72 69 67 68 74 20 28 63 29 20 31* *Copyright
112-127 39* 39* 34* 20 53 65 61 67 61 74 65 20 41 6C 6C 20 notice
128-143 72 69 67 68 74 73 20 72 65 73 65 72 76 65 64 20
144-147 D# D# D# D#

* Copyright year (changes with actual year).
** 01 = SCSI-1 implemented.

02 = SCSI-2 implemented (default).
The drive can be changed between these two configurations.

*** 01 = Response data is in SCSI-1 format and has compatibility with Common Command Set data.

02 = Response data is in SCSI-2 format (default).

The drive can be changed between these two configurations.
R# Four ASCII digits representing the last four digits of the product firmware release number.
S# Eight ASCII digits representing the eight digits of the product serial number.
D# Reserved 0000.
[ ] Bytes 18 through 23 reflect the model of the drive (ST12450W shown).

SCSI-2 Interface Product Manual.

11.3.2 Mode sense data

The following tables list the data-byte values the drive returns in response to
the Mode Sense command pages for SCSI-1 and SCSI-2 implementations
(see the

Definitions:
DEF = Default value. Standard drives are shipped configured this way.
CHG = Changeable bits; indicates if default value is changeable.

SCSI-2 Interface Product Manual).

ST12450W/WD Product Manual, Rev. B 51

Table 5. Mode sense data, Barracuda 2, 2HP default values

(SCSI-1 implementation)

Bytes 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Mode
Sense 63 00 10 08
Data 00 37 1B 38 00 00 02 00

<—————————Mode page headers and parameter data bytes—————————>

Mode
Page

DEF

01 81 06 04 1B 30 00 00 FF

CHG

01 81 06 EF FF 00 00 00 00

DEF

02 82 0A 80 80 00 0A 00 00 00 00 00 00

CHG

02 82 0A FF FF 00 00 00 00 00 00 00 00

DEF

03 83 16 00 09 00 09 00 00 00 09 00 95 02 00 00 01 00 0D 00 1C 40 00 00 00

CHG

03 83 16 FF FF FF FF 00 00 FF FF 00 00 00 00 00 00 00 00 00 00 00 00 00 00

DEF

04 84 12 00 0A 97 09 00 00 00 00 00 00 00 00 00 00 00 00 00 00

CHG

04 84 12 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 03 FF 00

DEF

08 88 12 10 00 FF FF 00 00 00 9F 02 7C 80 03 00 00 00 00 00 00

CHG

08 88 12 BD 00 00 00 FF FF FF FF 00 00 ADFF 00 00 00 00 00 00

DEF

00 80 02 00 00

CHG

00 80 02 76 00

52 ST12450W/WD Product Manual, Rev. B

Table 6. Mode sense data, Barracuda 2, 2HP default values

(SCSI-2 implementation)

Bytes 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Mode
Sense 9F 00 10 08
Data 00 3F 1B 38 00 00 02 00

<—————————Mode page headers and parameter data bytes—————————>

Mode
Page

DEF

01 81 0A 04 1B 30 00 00 00 03 00 FF FF

CHG

01 81 0A EF FF 00 00 00 00 FF 00 00 00

DEF

02 82 0E 80 80 00 0A 00 00 00 00 00 00 00 00 00 00

CHG

02 82 0E FF FF 00 00 00 00 00 00 00 00 83 00 00 00

DEF

03 83 16 00 09 00 09 00 00 00 09 00 95 02 00 00 01 00 0D 00 1C 40 00 00 00

CHG

03 83 16 FF FF FF FF 00 00 FF FF 00 00 00 00 00 00 00 00 00 00 00 00 00 00

DEF

04 84 16 00 0A 97 09 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1C 20 00 00

CHG

04 84 16 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 03 FF 00 00 00 00 00

DEF

07 87 0A 00 1B 30 00 00 00 00 00 FF FF

CHG

07 87 0A 0F FF 00 00 00 00 00 00 00 00

DEF

08 88 12 10 00 FF FF 00 00 00 9F 02 7C 80 03 00 00 00 00 00 00

CHG

08 88 12 BD 00 00 00 FF FF FF FF 00 00 A0 FF 00 00 00 00 00 00

DEF

0A 8A 0A 00 10 00 00 00 00 00 00 00 00
CHG

0A 8A 0A 03 01 00 00 00 00 00 00 00 00
DEF

0C 8C 16 80 00 00 18 00 00 00 00 00 00 00 0A 96 08 00 00 00 00 00 00 10 00

CHG

0C 8C 16 04 00 00 00 FF FF 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

DEF

00 80 02 00 00

CHG

00 80 02 76 00

ST12450W/WD Product Manual, Rev. B 53

11.4 SCSI bus conditions
and miscellaneous features supported

Asynchronous SCSI bus conditions supported by the drive are listed in
T able 7. These conditions cause the SCSI device to perform certain a ctions
and can alter the phas e sequence. Other miscellaneous operating features
supported are als o listed here.

Table 7. SCSI bus conditions and other miscellaneous features
Condition/feature supported by:

SCSI-1 SCSI-2 Conditions or feature

Y Y Attention condition
Y Y Reset condition
N Y Contingent allegiance condition
N Y Asynchronous event notification
Y Y Arbitrating system
Y Y Disconnect/reconnect
Y Y Asynchronous data transfer
Y Y Synchronous data transfer
Y Y Synchronized (locked) spindle operation
Y Y Differential interface circuits available
Y Y Segmented caching
N N Zero latency read
N Y Queue tagging (up to 64 queue tags supported)
N Y Deferred error handling
Y Y Parameter rounding (controlled by round bit

in Mode Select page 0)

N Y Reporting actual retry count in extended sense

bytes 15,16, and 17
N N Adaptive caching
Y Y Adaptive read lookahead
Y Y SMP = 1 in Mode Select command needed to

save RPL and rotational offset bytes

(in Table 5.2.1-25 of

Manual, Vol. 2).

SCSI-2 Interface Product

SCSI-1 SCSI-2 Status supported

Y Y Good
Y Y Check condition
Y Y Condition met/good
Y Y Busy
Y Y Intermediate/good
Y Y Intermediate/condition met/good
Y Y Reservation conflict
Y Y Queue full

54 ST12450W/WD Product Manual, Rev. B

11.5 Synchronous data transfer

The data transfer period to be used by the drive and the initiator is established
by an exchange of messages during the Message Phase of operation. See
the section on message protocol in the

11.5.1 Synchronous data transfer periods supported

Table 8 lists the synchronous data transfer periods supported by the drive.

Table 8. Synchronous data transfer periods

M Transfer period Transfer rate

(decimal) (M times 4 nanoseconds) (mega transfers/second)

25 100 10.0
31 125 8.0
37 150 6.66
50 200 5.0
62 250 4.00
75 300 3.33
87 350 2.86

100 400 2.5

SCSI-2 Interface Product Manual.

11.5.2 REQ/ACK offset

The maximum REQ/ACK offset supported by Barracuda drives is 15 (0Fh).

11.6 DC cable and connector

The drive receives DC power through a 4-pin connector mounted at the rear
of the main PCB (see Figure 17). Recommended part numbers of the mating
connector are listed below, but equivalent parts may be used.

Table 9. Mating connector parts
Type of cable Connector Contacts (20-14 AWG)

14 AWG AMP 1-480424-0 AMP 60619-4 (loose piece)

Note. The output of a power supply must meet SELV (safety extra low

voltage), as defined in IEC 950.

Pins

4

3

1 +12V DC

12

2 +12V DC return
3 +5V DC return
4 +5V DC

AMP 61117-4 (strip)

ST12450W/WD Product Manual, Rev. B 55

SCSI I/O

Connector

DC Power
Connector

J4

J01

Pin 1

J5

11.7 SCSI physical interface

Figure 17 shows the locations of the physical interface components for the
drive. Locations of the DC power connector, the SCSI interface connector,
the I/O line terminators, and the drive select and option select headers are
shown.

Details of the physical, electrical, and logical characteristics are given below.
The SCSI operational aspects of Seagate drive interfaces are provided in the

SCSI-2 Interface Product Manual.

Figure 17. Barracuda 2, 2HP physical interface

11.7.1 Physical characteristics

This section defines the connectors, cables, signals, terminators and bus
timing needed to implement the SCSI interface.

11.7.1.1 Physical description

You can daisy-chain multiple SCSI devices on a common cable if each
device has the same type of drivers and receivers (all single-ended or all
differential). Devices having single-ended interface circuits cannot be on the
same daisy chain with devices having a differential interface circuit. Both
ends of the cable must be terminated. All signals are common between SCSI
devices. A maximum of 16 SCSI devices (including the host) may be daisy­chained together.

T erminate both ends o f the daisy chain, but do not terminate any intermedi­ate SCSI device. The ST12450W drives are equipped with permanently
mounted IC terminators, which you can turn on or off using the Enable Drive
Terminator jumper on pins 11 and 12 of J4. The differential (ST12450WD)
drives do not have on-board t ermina tors.

11.7.1.2 Cable requirements

Sections 11.7.1.2.1, 11.7.1.2.2, and 11.7.1.2.3 describe the single-ended,
differential, and general cable requirements for Barracuda 2, 2HP drives.

56 ST12450W/WD Product Manual, Rev. B

11.7.1.2.1 Single-ended I/O circuits

The maximum total cable length for use with drives having single-ended I/O
driver and receiver circuits is 6 meters (19.7 feet) when operating at line data
transfer rates of 5 Mbytes/second or less, and 3 meters (9.85 feet) when
operating at transfer rates greater than 5 Mbytes/second (fast SCSI). A stub
length of no more than 0.1 meter (0.33 feet) is allowed off the mainline
interconnection with any connected equipment. An ideal impedance match
with cable terminators implies a cable characteristic impedance of 132 ohms.
Single-ended I/O cable pin assignments for ST12450W drives are shown in
Table 10.

11.7.1.2.2 Differential I/O circuits

The maximum total cable length for use with drives having differential I/O
drivers and receiver circuits is 25 meters (82 feet). A stub length of no more
than 0.2 meter (0.66 foot) is allowed off the mainline interconnection with any
connected equipment. An ideal impedance match with cable terminators
implies a cable characteristic impedance of 122 ohms. Differential I/O cable
pin assignments for ST12450WD drives are shown in Table 11.

11.7.1.2.3 General cable characteristics

In general, cables having the characteristic impedances given in Sections

11.7.1.2.1 and 11.7.1.2.2 are not available; however, impedances that are
lower are satisfactory. A characteristic impedance of 100 ohm +10% is
recommended for unshielded flat or twisted-pair ribbon cable. To minimize
discontinuities and signal reflections, cables of different impedances should
not be used in the same bus. Your specific setup may require tradeoffs in
shielding effectiveness, cable length, the number of loads, transfer rates, and
cost to achieve satisfactory system operation. If shielded and unshielded
cables are mixed within the same SCSI bus, the effect of impedance
mismatch must be carefully considered. Proper impedance matching is
especially important to maintain adequate margin at fast SCSI transfer rates.

11.7.2 Connector requirements

Recommended mating wide cable connectors part numbers:

AMP 786096-7, female 68-pin
AMP 786090-7, male 68-pin

11.7.3 Electrical description

ST12450W drives use single-ended interface signals. These signals must be
terminated with 110 ohm active terminator circuits at each end of the total
cable. Single-ended circuits use open collector or three-state drivers.
ST12450W drives can be configured to provide the SCSI termination.

ST12450WD drives use differential interface signals. Each of these signals
must be terminated at each end of the total cable with 330 ohms to +5V and
330 ohms to ground with 150 ohms between each differential pair. All I/O
circuits are open collector, three-state drivers. Differential I/O drives are
shipped without terminators and have no provisions for adding terminator
sockets on the PCB. You must provide external termination for these drives.

ST12450W/WD Product Manual, Rev. B 57

11.7.3.1 Single-ended drivers/receivers

Typical single-ended driver and receiver circuits for the Barracuda 2, 2HP
family are shown in Figure 18. Terminator circuits shown are needed only
when the disc drive is first or last on the daisy chain. (See Note 1 following
Figure 18.)

Note. All single-ended terminators must be ANSI SCSI-2 alternative 2

active terminators.

Transmitter characteristics

Single-ended drives use an ANSI SCSI compatible open-collector single­ended driver. This driver is capable of sinking a current of 48 mA with a low­level output voltage of 0.4V.

Receiver characteristics

Single-ended drives use an ANSI SCSI single-ended receiver with hyster­esis gate or equivalent as a line receiver.

Line Driver

Transmitter

(or transceiver)

[2]

Figure 18. Single-ended transmitters and receivers

[4]

[1]

+2.85V



110

Ohm

Flat

Cable

Pair

[3]

Line Receiver

[4]

+2.85V

110

[1]

Ohm

Receiver



[2]

Notes:

[1] Part of active terminator circuits. Enable drive termination when it is first

or last on the daisy chain.
Interface signal levels and logical sense at the drive I/O connector are

defined as follows:

Logic level Driver output Receiver input

Negated (0) ≥ 2.5V :≤5.25V ≥2.0V: <5.25V
Asserted (1) ≤0.4V:≥0.0V ≤0.8V: >0.0V

The difference in the voltages between input and output signals is due to

losses in the cable.
[2] ANSI SCSI compatible circuits.
[3] Total interface cable length should not exceed that specified in Section

11.7.1.2.1.

[4] Source of drive terminator power is VR1 which has an input source

voltage selected by a jumper.

58 ST12450W/WD Product Manual, Rev. B

11.7.3.2 Differential drivers/receivers

Typical differential driver and receiver circuits used by ST12450WD drives
are shown in Figure 19. The differential drives have no provisions for
terminator circuits.

Differential signals

All dif ferential in terface sig nals consis t of t wo lines denoted +SIGNAL
and –SIGNAL. A signal is true when +SIGNAL is more positive than
–SIGNAL, and a signal is false when –SIGNAL is more positive than
+SIGNAL. All assigned signals must be terminated at each end of the cable.
You mu st prov ide ex terna l ter minat ion fo r the differen tial dr ive s.

Output characteristics

Each signal driven by differential interface drives should have the following
output characteristics when measured at the disc drive’s SCSI connector:

Low-level output voltage*

= 2.0V maximum at low-level output current
= 55 milliamps

High-level output voltage*

= 3.0V minimum at high-level output current
= –55 milliamps

Differential voltage

= 1.0V minimum with common-mode voltage ranges

from –7V DC to +12V DC

* Measure these voltages between the output terminal and the SCSI

device’s logic ground reference.

The output characteristics must additionally conform to EIA RS-485-1983.

ST12450W/WD Product Manual, Rev. B 59

Input characteristics

Each signal received by differential interface drives should have the following
input characteristics when measured at the disc drive SCSI connector:

Input current on either input

= +2.0 milliamps maximum

(includes both receivers and passive drivers)

This requirement is met with the input voltage varying between –7V DC and
+12V DC, with power on or off, and with the hysteresis equaling 35 mV
minimum.

The input characteristics must additionally conform to EIA RS-485-1983.

+5V

+5V

5.6K

Transmit/Receive

Enable [1]

Transmit or
Receive
Signal [2]

Figure 19. Typical differential I/O line transmitter/receiver and terminators

DE

LSI

XCVR

RE

R2

1
1

[3]

[4]

Notes:

[1] Positive logic enables transmitter (+5V = asserted).

Negative logic enables receivers (0V = asserted).
[2] Negative logic signal (0V = asserted).
[3] Total interface cable length should not exceed 82.1 feet (25 meters) from

the host to the end of the daisy chain.
[4] You must provide terminators.

60 ST12450W/WD Product Manual, Rev. B

11.7.3.3 Terminator requirements
ST12450W

Internal disc drive I/O termination consists of 110 ohm active terminator
circuits contained in permanently mounted IC terminator packs on the main
PCB. All single initiator/single target (non-daisy-chain) applications require
you to terminate the initiator and drive.

You must terminate both ends of the SCSI bus with ANSI SCSI-2 standard
alternative 2 (active) termination, especially if the bus operates at fast SCSI
transfer rates.

Daisy-chain configurations require you to terminate only the units at each
end of the daisy chain. Do not terminate any other peripheral on the chain.

Note. Remove the Enable Drive Terminator jumper on J4 pins 11 and 12

when terminators are not required.

ST12450WD

Differential I/O Barracuda drives do not have provisions to add terminator
sockets on the PCB. You must provide external termination.

11.7.3.4 Terminator power

The drive may be configured to accept terminator power using pins 51 and
52 of the SCSI bus to supply power to the SCSI bus or to provide terminator
power for optional internal termination resistors using the drive’s power
connector (see Figure 14). The drive can provide power both to its own
terminators and to the SCSI bus terminator power line.

SCSI devices providing terminator power (TERMPWR) must have the
following characteristics:

• V TERM = 4.50V to 5.25V

• 800 mA minimum source drive capability

• 1.0A maximum

ST12450W/WD Product Manual, Rev. B 61

11.8 SCSI wide physical interface

Position 1

68 Position SCSI Receptacle
AMPLIMITE .050 Series

.008

Typ

(.20)

Figure 20. Wide SCSI device connector

1.368

(34.75)

.767

(19.46)

Position 1

.740

(18.8)

12 Position Auxiliary
Shrouded Post Header
AMPMODU 2mm

.010

Typ

(.25)

.300

(7.62)

.870

(22.1)

4 Position Power
Header, Commercial
Mate-N-Lock

.315

(8.00)

Position 1

.403

(10.24)

.033
(.84)

Typ

.015
(.38)

62 ST12450W/WD Product Manual, Rev. B

Table 10. Single-ended contact assignments (P cable)

for ST12450W drives

Signal Connector Connector Signal
name contact number contact number name

GROUND 1 35 –DB (12)
GROUND 2 36 –DB (13)
GROUND 3 37 –DB (14)
GROUND 4 38 –DB (15)
GROUND 5 39 –DB (P1)
GROUND 6 40 –DB (0)
GROUND 7 41 –DB (1)
GROUND 8 42 –DB (2)
GROUND 9 43 –DB (3)
GROUND 1 0 44 –DB (4)
GROUND 1 1 45 –DB (5)
GROUND 1 2 46 –DB (6)
GROUND 1 3 47 –DB (7)
GROUND 14 48 –DB (P)
GROUND 15 49 GROUND
GROUND 16 50 GROUND
TERMPWR 17 51 TERMPWR
TERMPWR 18 52 TERMPWR
RESERVED 19 53 RESERVED
GROUND 20 54 GROUND
GROUND 21 55 –ATN
GROUND 22 56 GROUND
GROUND 23 57 –BSY
GROUND 24 58 –ACK
GROUND 25 59 –RST
GROUND 26 60 –MSG
GROUND 27 61 –SEL
GROUND 28 62 –C/D
GROUND 29 63 –REQ
GROUND 30 64 –I/O
GROUND 3 1 65 –DB (8)
GROUND 3 2 66 –DB (9)
GROUND 3 3 67 –DB (10)
GROUND 3 4 68 –DB (11)

Notes:

1. The hyphen preceding a signal name indicates that signal is active low.

2. 8-bit devices that connect to the P cable should leave the following

signals open: DB(8) –DB(9) –DB(10) –DB(11) –DB(12) –DB(13) –DB(14)
–DB(15) –DB(P1). All other signals should be connected as defined.

ST12450W/WD Product Manual, Rev. B 63

Table 11. Differential contact assignments (P cable)

for ST12450WD drives

Signal Connector Connector Signal
name contact number contact number name

DB (12) 1 35 –DB (12)
DB (13) 2 36 –DB (13)
DB (14) 3 37 –DB (14)
DB (15) 4 38 –DB (15)
DB (P1) 5 3 9 –DB (P1)
GROUND 6 40 GROUND
DB (0) 7 41 –DB (0)
DB (1) 8 42 –DB (1)
DB (2) 9 43 –DB (2)
DB (3) 10 44 –DB (3)
DB (4) 11 45 –DB (4)
DB (5) 12 46 –DB (5)
DB (6) 13 47 –DB (6)
DB (7) 14 48 –DB (7)
DB (P) 15 49 –DB (P)
DIFFSENS 16 50 GROUND
TERMPWR 17 51 TERMPWR
TERMPWR 18 52 TERMPWR
RESERVED 19 53 RESERVED
ATN 20 54 –ATN
GROUND 21 55 GROUND
BSY 22 56 –BSY
ACK 23 57 –ACK
RST 24 58 –RST
MSG 25 59 –MSG
SEL 26 60 –SEL
C/D 27 61 –C/D
REQ 28 62 –REQ
I/O 29 63 –I/O
GROUND 30 64 GROUND
DB (8) 31 65 –DB (8)
DB (9) 32 66 –DB (9)
DB (10) 33 67 –DB (10)
DB (11) 34 68 –DB (11)

Notes:

1. The hyphen preceding a signal name indicates that signal is active low.

2. 8-bit devices that connect to the P cable should leave the following signals
open: –DB(12) –DB(13) –DB(14) –DB(15) –DB(P1) –DB(8)
–DB(9) –DB(10) –DB(11) DB(12) DB(13) DB(14) DB(15) DB(P1) DB(8)
DB(9) DB(10) DB(11). All other signals should be connected as defined.

64 ST12450W/WD Product Manual, Rev. B

Table 12. Disc drive SCSI timing

Waveform Waveform

Description symbol [1] table [1] Typical Max

Target select time (no arbitration) T00 N/A < 1 µs < 250 µs
Target select time (with arbitration) T01 4.5-1,2 2.31 µs 2.36 µs
Target select to command T02 4.5-1 3.33 µs 3.34 µs
Target select to MSG out T03 4.5-2 1.51 µs 1.54 µs
Identify MSG to command T04 4.5-3 3.34 µs 3.36 µs
Command to status T05 4.5-5 Command dependent
Command to data (para. in) T06 4.5-9 Command dependent
Command to data (para. out) T07 4.5-10 Command dependent
Command to data (write to data buffer) T08 4.5-10 Command dependent
Command to disconnect MSG T09 4.5-6 Command dependent
Disconnect MSG to bus free T10 4.5-6,14 0.64 µs 0.68 µs
Disconnect to arbitration (for re-select) T11 4.5-6 Command dependent

This measures disconnected CMD overhead
Target win arbitration (for re-select) T12 4.5-7 2.8 µs
Arbitration to re-select T13 4.5-7 1.8 µs
Re-select to Identify MSG in T14 4.5-7 1.34 µs
Re-select Identify MSG to status T15 4.5-8 Command dependent
Re-select Identify MSG to data (media) T16 4.5-11 Command dependent
Data to status T17 4.5-15 Command dependent
Status to command complete MSG T18 4.5-5,8,15 1.0 µs
Command complete MSG to bus free T19 4.5-5,8,15 0.75 µs
Data to save data pointer MSG T20 4.5-14 4.5 µs
Save data pointer MSG to disconnect MSG T21 4.5-14 0.75 µs
Command byte transfer T22 4.5-4 0.04
Next command byte access 4.5-4

Next CDB byte access (byte 2 of 6) T23.6.2 4.5-4 0.55 µs 0.56 µs
Next CDB byte access (byte 3 of 6) T23.6.3 4.5-4 0.10 µs 0.10 µs
Next CDB byte access (byte 4 of 6) T23.6.4 4.5-4 0.09 µs 0.10 µs
Next CDB byte access (byte 5 of 6) T23.6.5 4.5-4 0.13 µs 0.14 µs
Next CDB byte access (byte 6 of 6) T23.6.6 4.5-4 0.13 µs 0.14 µs

T33

T34
Next CDB byte access (byte 2 of 10) T23.10.2 4.5-4 0.59 µs 0.60 µs
Next CDB byte access (byte 3 of 10) T23.10.3 4.5-4 0.14 µs 0.14 µs
Next CDB byte access (byte 4 of 10) T23.10.4 4.5-4 0.13 µs 0.14 µs
Next CDB byte access (byte 5 of 10) T23.10.5 4.5-4 0.12 µs 0.12 µs
Next CDB byte access (byte 6 of 10) T23.10.6 4.5-4 0.11 µs 0.12 µs
Next CDB byte access (byte 7 of 10) T23.10.7 4.5-4 0.10 µs 0.10 µs
Next CDB byte access (byte 8 of 10) T23.10.8 4.5-4 0.09 µs 0.10 µs
Next CDB byte access (byte 9 of 10) T23.10.9 4.5-4 0.13 µs 0.14 µs
Next CDB byte access (byte 10 of 10) T23.10.10 4.5-4 0.12 µs 0.12 µs

continued

ST12450W/WD Product Manual, Rev. B 65

continued from previous page

Waveform Waveform

Description symbol [1] table [1] Typical Max

Data in byte transfer (parameter) T24 4.5-12 0.04 µs
Data out byte transfer (parameter) T25 4.5-13 0.04 µs
Next data in byte access (parameter) T26 4.5-12 0.10 µs 0.12 µs
Next data out byte access (parameter) T27 4.5-13 0.10 µs 0.12 µs
Data in byte transfer (media) [2] T28 4.5-12 0.03 µs 0.04 µs
Data out byte transfer (media) [2] T 29 4.5-13 0.03 µs 0.04 µs
Next data in byte access (media) [2] T30 4.5-12 0.10 µs 0.12 µs
Next data out byte access (media) [2] T31 4.5-13 0.10 µs 0.12 µs
MSG IN byte transfer T32 4.5-5,7 0.09 µs 0.04 µs

4.5-8,14,15
MSG OUT byte transfer T33 4.5-2 0.04 µs
STATUS byte transfer T 34 4.5-5,8 0.04 µs

4.5-15
Synchronous data transfer characteristics:

Request signal transfer period [3] – – various 800 ns

Notes:

[1] See the
[2] Maximum SCSI asynchronous interface transfer rate is given in Section 5.3.
[3] Synchronous transfer period is determined by negotiations between an initiator and a drive. The

drive is capable of setting periods as given in Section 11.5 in this manual. See also Sections 3.1.5.2
and 3.5.3.2 of the
operation.

SCSI-2 Interface Product Manual

SCSI-2 Interface Product Manual

(part number 77738479), Section 4.5.

for a description of synchronous data transfer

General timing diagrams for SCSI interface operation are shown in the

Manual,

Section 4.5.

SCSI-2 Interface Product

ST12450W/WD Product Manual, Rev. B 67

Index

A

AC power requirements 29
acoustics 34
active termination 56, 60
actuator assembly 6
adapter accessory frame kit 8
adaptive read lookahead 16
air cleanliness requirements 34
air flow 22
altitude, effective limits 32
ambient temperature range 32
ANSI, documents 3
asynchronous

data transfer protocol 7

SCSI bus conditions supported 53
automatic shipping lock 6, 7
automatic thermal compensation 7, 11
autowrite and read reallocation 7

B

bits per inch, number of 11
bytes

per sector , allow a ble r ange 7

per surface, n umber of 11

per track, number of 11

C

cable requirements 55
cache control 15
caching write data 17
capacities

formatted 8

modifying 8

unformatted 8
conducted noise immunity 30
connector parts, DC power connection 54
contact assignments (P cable)

differential 63

single-ended 62
cooling. mechanical 36
current requirements 29

D

data block size, modifying the 8
data buffer 7
data buffer to/from disc media (512-b yte sector)

data transfer rate (< 1 track) 14

data transfer rate (≤ sector) 14
data heads, number of 11
data zone 6
DC cable and connector 54
DC power requirements 29
defect and error management 39
defects and errors

ETF defect list 39

primary defect list 39
Delay Motor Start option 43
diameter, media (disc) 37
differential drivers/receiv ers 58

terminating 58
differential I/O , cab le requirements 56
digital offset values 19
dimensions, J5 physical interface 45
disc rotation speed 11
disconnect/reconnect 5
drive failure, defined 22
drive orientation 36
drivers and receivers 44

E

effective altitude (sea level) 32
electromagnetic compatibility 34
electromagnetic interference (EMI) 21
EMC/regulatory requirements, meeting 3
Enable Drive Terminator 43
Enable Motor Start option 43
environmental interference 21
environmental limits

effective altitude 32

shock and vibration 33

temperature 32
error correction code 7
error rates 21

F

fans, positioning for cooling 22
features, listed 7
firmware 7

68 ST12450W/WD Product Manual, Rev. B
flaw reallocation performance impact 14

flawed sector reallocation 7
format drive command execution time

for ≥ 512-byte sectors 13
formatting 9
front panel kit (with green lens) 8

G

grounding 45
GYHX, measuring 24

H

head and disc assembly (HDA) 5

cooling 22
head switch, overhead time 14
heat/power dissipation 32
hot plugging Barracuda disc drives 26
humidity 32

I

index signal 18
inquiry data 50
installation 26

instructions 9

plug and play 26

service tools 26
interface requirements 47
interleave 7

minimum sector 14
internal data rate 11

J

J4 (J04), jumper connector 43
J5 (J05), jumper connector 43
jumper connectors

explained 43

illustrated 42

L

landing zone 6

M

mean time between failures (MTBF) 22
mechanical specifications

depth 35

height 35

weight 35

width 35

media characteristics 37
media description 37
miscellaneous

operating features supported 53
miscorrected data transferred 21
Mode Select command 15
Mode Sense data 50
Motor Start command 15
MTBF 21
multiple initiators 5

N

96-bit Reed-Solomon error correction code 7
noise

defined 30
maximum allowed 30

O

offset values 19
one track cylinder switch, overhead time 14
operating current 29
option/configuration headers 41
options

adaptor accessory frame kit 8
Barracuda 2, 2HP Installation Guide 8
front panel 8
single-unit shipping pack 8

P

panel, front kit 8
Parity Disable option 43
performance

general 7, 14

list of characteristics 11
physical rotational offsets 19
physical/electrical specifications 29
power control switch 15
power dissipation 6
power requirements

AC 29

DC 29
prefetch/multi-segmented cache control 15
preventive maintenance 7, 21, 26

R

radiated emissions, characterizations 3
reallocation of defects on command

(post format) 7

ST12450W/WD Product Manual, Rev. B 69
recoverable error rate 21

Reed-Solomon error correction code 7
reference documents

Barracuda 2, 2HP Installation Guide 3
SCSI-2 Reference Manual 3

reference index signal 44

termination 45
reference signal 18, 19
relative humidity

non-operating 32

operating 32
reliability

general characteristics 7

service, and 22

specifications 21
REQ/ACK offset 54
rotation speed 11
rotational

latency , average 11

position locking 18

skew, operating the drive with 19
RYHX, measuring 25

S

safety agencies, certification 3
safety/regulatory agency compliance 3
SCSI bus conditions and misc. features 53
SCSI drivers and receivers 7
SCSI interface

cable connector requirements 56

electrical description

differential driv ers/receivers 58

single-ended drivers/receivers 56
messages supported 47
physical connections 55
terminator requirements 60
transfer rate 14

SCSI physical interface 55
sector reallocation scheme 7
sector size, allowable range 7, 14
seek error rate 21
seek errors 22

defined 22

seek times, listed 13
self-configuring host software 5
service

life 21, 26

service

philosophy 26

tools 26
servo heads, number of 11
shock

non-operating 33

operating

abnormal 33
normal 33

packaged 33
shock and vibration 33
single-unit shipping pack kit 8
single-ended

SCSI drivers and receivers 7

drivers/receivers, terminating 57

I/O, cable requirements 56
spare reallocation 8
spindle

stopping with the Motor Start command 15

brake 7

synchronization mode,

enabling and disabling 19
start current 29
start/stop time 15
synchronized

drive interconnect diagram 17
spindle operation 17
spindles interface 44
electrical description 44

synchronous data transfer

periods supported 54
protocol 7

synchronous spindle 7

T

temperature, operating 32
terminating SCSI devices 55
terminator power 60

options 43
terminator requirements 60
tracks

per inch, number of 11

per surface, number of 11
12V current profile 31

70 ST12450W/WD Product Manual, Rev. B

U

UL 3unit attention 19
unrecoverable

error, defined 21
write errors, defined 21

unrecovered data transferred 21

V

vibration

non-operating 34
operating

abnormal 34

normal 34
VIC 2 LSI 18
voltage requirements 29

W

write data, caching 17
write errors 21
Write Protect option 43

Z

zone bit recording (ZBR) 7

Seagate Technology, Inc.
920 Disc Drive, Scotts Valley, California 95066-4544, USA

Publication Number: 83328900, Rev. B, Printed in USA