seagate ST15150N, ST15150W Installation guide

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Barracuda 4 Disc Drive

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

ST15150N/ND

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ST15150W/WD/WC/DC

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Product Manual, Volume 1

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

Barracuda 4 Disc Drive

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

ST15150N/ND

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

ST15150W/WD/WC/DC

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

Product Manual, Volume 1

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

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 06/27/94 L. Newman/J. Olson All B 03/08/95 L. Newman/J. Olson 1, 8, 9, 14, 17, 24, 25,

26, 27, 28, 29, 30, 31, 35, 36, 37, 38, 39, 43, 49, 53, 54, 55, 56, 57, 59, 60, 61, 62, 63, 66, 67, 68, 70, 71, 72, 74, 75, 82, 83, 84.

C 06/07/95 L. Newman/J. Olson 11, 12, 29, 33, 34, 35,

36, 41, 42, 54, 59, 60, 61, 62, 65, 70, 71

D 02/07/96 L. Newman/J. Olson 1, 3, 40, 41, 48, 49,

51, 52, 53, 59, 60, 61, 62, 65, 68, 70

Note. Product Manual 83328880 is Volume 1 of a two-volume

document with the SCSI interface information in the

2 SCSI-2 Interface Product Manual,

Part Number 77738479.

Volume

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

4.3.1 Front panel....................................................................................................... 8

4.3.2 Single-unit shipping pack ................................................................................. 8

4.3.3 Barracuda 4 Installation Guide ......................................................................... 8

4.3.4 Adaptor accessory frame kit ............................................................................ 8

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

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

5.1 Internal drive characteristics ....................................................................................... 1 1

5.2 SCSI seek performance characteristics ...................................................................... 1 1

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

5.6 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 .................................................................................30

6.2.4 Service life ......................................................................................................30

6.2.5 Service philosophy..........................................................................................30

6.2.6 Installation.......................................................................................................30

6.2.7 Service tools ...................................................................................................30

6.2.8 Hot plugging Barracuda 4 disc drives .............................................................31

7.0 Physical/electrical specifications .....................................................................................33

7.1 AC power requirements ..............................................................................................33

7.2 DC power requirements ..............................................................................................33

7.2.1 Conducted noise immunity..............................................................................34

7.2.2 Power sequencing ..........................................................................................34

7.2.3 12V current profile ..........................................................................................35

7.3 Heat/power dissipation................................................................................................36

7.4 Environmental limits....................................................................................................36

7.4.1 T emperature....................................................................................................36

7.4.2 Relative humidity ............................................................................................36

7.4.3 Effective altitude (sea level) ............................................................................37

7.4.4 Shock and vibration ........................................................................................37

7.4.5 Air cleanliness.................................................................................................38

7.4.6 Acoustics ........................................................................................................38

7.5 Electromagnetic compatibility......................................................................................38

7.6 Mechanical specifications ...........................................................................................39

7.6.1 Drive orientation..............................................................................................42

7.6.2 Cooling ...........................................................................................................42

8.0 Media characteristics ........................................................................................................43

8.1 Media description........................................................................................................43

9.0 Defect and error management ..........................................................................................45

9.1 Drive internal defects/errors ........................................................................................45

10.0 Drive configuration............................................................................................................47

10.1 Option headers ...........................................................................................................47

10.1.1 ST15150N/ND drives option headers .............................................................47

10.1.2 ST15150W/WD drives option headers ............................................................50

10.1.3 ST15150WC/DC drives option headers ..........................................................53

10.2 Synchronized spindles interface .................................................................................55

10.2.1 Electrical description.......................................................................................55

10.3 Grounding...................................................................................................................57

10.4 Drive termination.........................................................................................................57

11.0 Interface requirements ......................................................................................................59

11.1 General description.....................................................................................................59

11.2 SCSI interface messages supported...........................................................................59

11.3 SCSI interface commands supported..........................................................................60

11.3.1 Inquiry data.....................................................................................................62

11.3.2 Mode sense data ............................................................................................63

11.4 SCSI bus conditions and miscellaneous features supported.......................................66

11.5 Synchronous data transfer..........................................................................................67

11.5.1 Synchronous data transfer periods supported ................................................67

11.5.2 REQ/ACK offset..............................................................................................67

11.6 DC cable and connector .............................................................................................67

11.7 SCSI physical interface...............................................................................................68

11.7.1 Physical characteristics ..................................................................................69

11.7.2 Connector requirements .................................................................................70

11.7.3 Electrical description .......................................................................................71

11.8 SCSI non-wide physical interface ...............................................................................75

11.9 SCSI wide physical interface.......................................................................................7 8

11. 10SCSI SCA physical interface.......................................................................................81

11.11Disc drive SCSI timing ................................................................................................84

Index ............................................................................................................................................87

Figures

Figure 1. Barracuda 4 disc drive ............................................................................................. 1

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

Figure 3. OEM interruptible thermal calibration implementation .............................................. 13

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

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

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

Figure 7. AYHX temperature measurement locations ............................................................. 24

Figure 8. LYHX temperature measurement locations.............................................................. 25

Figure 9. MYHX temperature measurement locations............................................................. 26

Figure 10. NYHX temperature measurement locations ............................................................. 27

Figure 11. JYHX temperature measurement locations.............................................................. 28

Figure 12. KYHX temperature measurement locations ............................................................. 29

Figure 13. Temperature measurement location......................................................................... 30

Figure 14. Typical Barracuda 4 drive +12V current profile......................................................... 35

Figure 15. Mounting configuration dimensions for N/ND drives ................................................. 39

Figure 16. Mounting configuration dimensions for W/WD drives ............................................... 40

Figure 17. Mounting configuration dimensions forWC/DC drives .............................................. 41

Figure 18. Recommended mounting ......................................................................................... 42

Figure 19. ST15150N/ND drives option header locations.......................................................... 47

Figure 20. ST15150N/ND drives option select jumper connectors ............................................ 48

Figure 21. ST15150W/WD drives option header locations ........................................................ 50

Figure 22. ST15150W/WD drives option select jumper connectors........................................... 51

Figure 23. ST15150WC/DC drives option header locations ...................................................... 53

Figure 24. ST15150WC/DC drives option select jumper connectors ......................................... 53

Figure 25. SCSI reference index signal driver/receiver combination ......................................... 55

Figure 26. ST15150N/ND drives configuration select header specification ............................... 56

Figure 27. ST15150W/WD drives configuration select header specification.............................. 56

Figure 28. ST15150N/ND drives physical interface ................................................................... 68

Figure 29. ST15150W/WD drives physical interface ................................................................. 68

Figure 30. ST15150WC/DC drives physical interface ............................................................... 68

Figure 31. Single-ended transmitters and receivers .................................................................. 72

Figure 32. Typical differential I//O line transmitter/receiver and terminators .............................. 73

Figure 33. Non-shielded SCSI device connector ....................................................................... 75

Figure 34. Wide SCSI device connector.................................................................................... 78

Figure 35. SCA SCSI device connector .................................................................................... 81

ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D 1

1.0 Scope

This manual describes Seagate Technology®, Inc. Barracuda™ 4 disc drives.

Barracuda drives support the Small Computer System Interface-2 ( SC SI-2 ) as described in the ANSI SCSI and SCSI-2 interface specifications to the extent described in this manual. This manual defines the performanc e characteristics of the Barracuda 4 drives. The

Manual

characteristics of this and other families of Seagate drives.

(part number 77738479) describes the general SCSI interfac e

N/ND type

SCSI-2 Interface Product

W/WD type

WC/DC type

Figure 1. Barracuda 4 disc drives

2 ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D

ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D 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.

If this model has the CE Marking, it complies with the European Union requirements of the Electromagnetic Compatibility Directive 89/336/EEC of 03 May 1989 as amended by Directive 92/31/EEC of 28 April 1992 and Directive 93/68/EEC of 22 July 1993.

Seagate uses an independent laboratory to confirm compliance to the above directives. Drives are tested in representative systems for typical applications. The selected system represents the most popular characteristics for test platforms. The system configurations include:

• 486, Pentium, and PowerPC Microprocessors

• 3.5-inch floppy disc drive

• Keyboard

• Monitor/display Although the test system with this Seagate model complies to the directives,

we cannot guarantee that all systems will comply. The computer manufacturer or system integrator shall confirm EMC compliance and provide CE Marking for their product.

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 4 Installation Guide

Seagate part number: 83328870

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.

4 ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D

ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D 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 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 4 disc drive (exploded view)

6 ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D

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 related reliability concerns.

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

ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D 7

4.0 Standard features

Barracuda 4 drives have the following standard features:

• 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

• Active termination for single-ended models

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

4.1 Performance

• 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

• 800,000 hour MTBF

• Adaptive seek velocity; improved seek performance

• LSI circuitry

• Balanced low-mass rotary voice-coil actuator

8 ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D

4.2 Unformatted and Formatted Capacities

Standard OEM models are formatted to 512 bytes per block. ST15150 drives have nine (9) spare sectors per cylinder and one (1) spare

cylinder per unit.

Formatted Unformatted

4,294 Mbytes 5,062 Mbytes

Users having the necessary equipment may modify the data block size before issuing a format command to obtain different formatted capacities. User-available capacity also depends on the spare reallocation sc heme selected. See the Mode Select command and the Format command in the

SCSI-2 Inte rfac e P r oduc t Manual

(part number 77738479).

4.3 Options

The following items are incorporated at the time of production or are available as accessories. All kits may be installed in the field.

• Front panel kit (green lens), part number 70869751

• Single-unit shipping pack kit

•

Barracuda 4 Installation Guide,

• Adapter accessory frame kit, part number 75790701 (adapts a 3.5-inch drive to fit in a 5.25-inch drive mounting space)

part number 83328870

4.3.1 Front panel

The front panel normally available 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.

4.3.2 Single-unit shipping pack

The drive is normally shipped in bulk packaging to provide maximum protection against transit damage. Units shipped individually require additional protection as provided by the single-unit shipping pack. Users planning single-unit distribution should specify this option.

4.3.3

Barracuda 4 Installation Guide

Part number 83328870 This manual provides basic information about how to install the drive. It also

includes information to assist in obtaining service for the drive.

4.3.4 Adaptor 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 form factor. It includes mounting hardware, front panel with a

green lens, an LED with cable that connects to the remote LED connector, and installation instructions.

ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D 9

4.4 Installation

For option jumper locations and definitions refer to Figures 20, 22, or 24. 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 (ST15150N/ W/WC) drives by enabling this feature with a jumper (see Section 10). External terminators are required for differential (ST15150ND/WD/DC) drives. These external terminators must be provided by the user, systems integrator, or host e quipment 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 the termination from the new drive.

• Set all appropri a te option jumpe rs prior to appl yin g pow er to the drive. If you change jumpers after applying power, recycle the drive’s power to make the new settings effective.

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.

10 ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D

ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D 11

5.0 Performance characteristics

This section provides performance-related characteristics and features of Barracuda 4 drives.

5.1 Internal drive characteristics

Drive capacity, Mbytes unformatted 5,062 Read/write data heads, maximum (physical) 2 1 Bytes per track, average bytes 64,160 Bytes per surface, Mbytes unformatted 232.4 Cylinders/tracks per surface, user accessible 3,711 Tracks per inch 4,048 Bits per inch 73,820 Servo heads 1 Internal data rate per physical head, Mbits/sec, 47.5 to 72.0

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

5.2 SCSI seek performance characteristics

ASA I download code thermal calibration (TCAL)

All performance characteris tics assum e that thermal calibration is no t in process when the drive receives the SCSI command. Thermal calibration will not interrupt an active SCSI command. If thermal calibration is in process when a SCSI command is received, the command is queued until the calibration for the specific head being calibrated completes. When calibration completes for the specific head being calibrated, the first queued SCSI command executes. When ex ecution of the first queued command is complete, the drive continues the calibration for the remaining head.

The above p roced ure c ontin ues unt il calibrat ion fo r all head s has co mpleted, or until 10 minutes have elapsed. The drive initiates a thermal calibration 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 initiat es thermal calibration cycle approximately once every 10 minutes . Automatic no n- i nte rr upt i bl e the r mal c alibrati o n oc cu rs at other times but should be transparent to the user (e.g., during format, Rezero command, at spindle-up, during read error recovery, and during reassign block functions). You can use the Rezero command to reset the thermal calibration timer back to its start so that the host knows when the interruption for thermal calibration will occur.

12 ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D

ASA II download code thermal calibration (TCAL)

1. All heads are thermally calibrated at power-up and following SCSI resets before any read or write commands are processed. All heads are also thermally calibrated during the SCSI Rezero Unit command.

2. The drive then delays a fixed period of time (D) before initiating any further thermal calibrations. This delay provides a guaranteed time interval when no thermal calibration interruptions will occur.

3. A single-head TCAL is scheduled to occur every N1 seconds where:

N1 = (T – D)/(2 • H) T = Maximum allowable thermal calibration period for any single

head (600 seconds) D = Time delay after the power-up/reset calibration before initiating

subsequent thermal calibrations (300 seconds) H = Number of heads in the drive (see Section 5.1 “Internal drive

characteristics”).

4. After the drive has cycled once through all the heads (H) at the N1 time interval, single-head TCAL scheduling switches to a N2 time interval where: N2 = T/(2 • H).

5. When a single-head TCAL is scheduled, the drive attempts to find an idle period of 25 to 50 milliseconds prior to performing the TCAL. If the TCAL has still not been performed after another N1 or N2 seconds (whichever is the current time interval) the drive forces a TCAL to occur at the next command boundary (even during a read look ahead sequence), and immediately resets the N1 or N2 timer. This guarantees that no head will remain uncalibrated for more than T (600) seconds and that no TCALs will occur closer together in time than approximately N1 or N2 seconds.

6. TCALs performed during the “standard” retry sequence are limited to the failing head, and will be disabled if the host selects a retry count of zero.

Refer to Section 11.11 and to the number 77738479) for additional timing details.

SCSI-2 Interface Product Manual

(part

ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D 13

Start

Has

10 min.

timer

expired?

Set

10 minute

timer

Yes

Is

SCSI

command in

progress?

Complete Command

Seek to

TCAL cyl and select head zero

TCAL

head

Has

target

received a SCSI

command?

Yes

All

heads

calibrated?

Yes

All

heads

calibrated?

Yes

Select

next

head

Has

target

received a SCSI

command?

Yes

Target

completes

SCSI

command

Seek to

TCAL cyl and select next head

Figure 3. OEM interruptible thermal calibration implementation

5.2.1 Seek time

Drive level (msec) without disconnect* (msec) read write read write

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

*Typical seek values are measured under nominal conditions of tempera-

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

5.2.2 Format drive command execution time for

Maximum (with verify) 60 minutes

≥≥

≥ 512-byte sectors

≥≥

Maximum (without verify) 40 minutes

Drive including controller overhead

14 ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D

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 5.30 Mbytes/sec* Maximum 8.94 Mbytes/sec*

Data transfer rate (< 1 track)

Minimum, divided by interleave factor 3.56 Mbytes/sec Maximum, divided by interleave factor 7.65 Mbytes/sec

Sector sizes

Default 512-byte data blocks Variable in even-sector sizes 180 to 4,096 bytes

SCSI interface data

Async. transfer rate, max instantaneous ST15150N/ND 5.0 Mbytes/sec*, ** ST15150W/WD/WC/DC 10.0 Mbytes/sec*, ***

Synchronous transfer rate fast ST15150N/ND 0.5 to 10.0 Mbytes/sec

Synchronous transfer rate wide

ST15150W/WD/WC/DC 0.5 to 20.0 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 m easur ed fr om the start o f the first s ector transfer t o or from the host.

** Assumes system ability to support 5.0 Mbytes/sec and no cable loss. ***Assumes system ability to support 1 0.0 Mbytes/sec and no cable loss.

ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D 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. If a recoverable error condition is detected during the start sequence, the drive executes a recovery procedure−this may cause the time it takes for the drive to become ready to exceed 30 seconds. During the start sequence, the drive responds to some commands over the SCSI interface. Stop time is less than 30 seconds after removing DC power. This means the motor starts as soon as power is applied. During this time the drive responds to some commands over the SCSI interface. Stop time is less than 30 seconds 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 an error recovery procedure, if needed). 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 that in many cases enhances system performance. To select this feature the host sends the Mode Select command with the proper values in the applicable bytes in page 08h (see the cache operation enabled.

Of the 1,024 Kbytes physical buffer space, approximately 954 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, if possible, 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 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:

SCSI-2 Interface Product Manual).

data requested by the host with a

If the cache is not enabled, 954

Default is prefetch and

Case A. Read command is received and the first logical block is already in the cache.

1. 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.

16 ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D

2. When a requested logical block is reached that is not in any segment, the drive fetches it and any remaining requested logical block addresses from the disc and puts them in a segment of the cache. The drive transfers the remaining requested logical blocks from the cache to the initiator in accordance with the “buffer-full” ratio specification given in Mode Select Disconnect/Reconnect parameters, page 02h (see the

SCSI-2 Interface

Product Manual).

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 value has been transferred (see the

Case B. 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

SCSI-2 Interface Product Manual)

SCSI-2 Interface Product

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.

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

SCSI-2 Interface

Product Manual).

Each cache segment is actually a self-contained circular buffer whose length is an integer number of sectors. The wrap-around capability of the individual segments greatly enhances the cache’s overall performance, allowing a wide range of user-selectable configurations, which includes a pure prefetch strategy. The drive supports operation of any integer number of segments from 1 to 16. Divide the 976,896 bytes in the buffer by the number of segments to get the segment size. Default is 3 segments. (See the

SCSI-2

Interface Product Manual.)

ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D 17

5.6 Caching write data

Write caching is a drive write operation that uses a drive buffer storage area where the data to be written to the disc is stored while the drive performs the Write command.

Write caching is enabled along with read caching. 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

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, the data is written into the beginning of the same cache segment, overwriting the 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.

SCSI-2 Interface Product Manual).

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 capacity and transfer rate in a cost-effective manner.

The interface consists of a twisted-pair cable that connects the drives in the synchronized system in a daisy-chain configuration as shown in Figure 4.

Note. ST15150WC/DC drives can use J6 pin 37 from the SCA connector

or J04 pin 6 for spindle sync.

Sync Interface

Master Sync

Source

Host

(or other drive)

System

Interface

Spindle Control

+5V

Drive 1

Spindle Control

+5V

Drive 2

Spindle Control

+5V

Drive n

1 2

Master Sync

Source

Host

(or other drive)

System

Interface

Sync Interface

Spindle

Control

+5V

Drive 1

Spindle

Control

+5V

Drive 2

Spindle

Control

+5V

Drive n

11 12

ST15150N/ND Drives ST15150W/WD Drives

Figure 4. Synchronized drive interconnect diagram

18 ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D

The host c an rec o nf ig ure the drive any t i me a f ter p ower- u p to be t he master or a slave by using the Mode Select command on the Rigid 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 that ca n be a drive or the host co m puter. All drives may be configured as slav es allowing the host t o pro vide the reference signal.

Each drive also can be config ured for t he non- syn chro nized mode in which it ignores any reference signal that might be present—this is the default mode as shipped from the factory. The connection of the synchronized reference signal to the host is required 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 Pike LSI on the master drive provides the reference signal (SSREF +). The index signal generates a 1 20 Hz signal. The signal is normally false/ negated (nominal 0V) and makes a transition to the true/asserted (nominal +5V) lev el to indicate the re fe ren ce p osi tio n du rin g th e r ev ol u- tion period. The master and slave drives use the trailing (falling) edge of the reference signal to phase-lock their spindles. A maximum of 10 seconds is allo wed for a slav e to synchroniz e with the refe rence signa l. Figure 5 shows the characteristics of the reference signal.

SSREF +

Figure 5. Synchronized reference signal characteristics

1.0 µsec min.

1.37 µsec max.

T = 0.0083 seconds ± 1.0% max ± 20 microseconds phase error while synchronized

ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D 19

SCSI interface factors The Rotational Position Locking (RPL) field in byte 17 (bits 0 and 1) of the

Rigid Disc Drive Geometry mode parameters page 04h is used for enabling and disabling spindle synchronization mode (see the

Product Manual).

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 Spindles Synchronized (5C01) or Spindles 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 Spindles Synchronized (5C01) or Spindles Not Synchronized (5C02).

You may operate the drive may with a rotational skew when synchronized. The rotational skew is applied in the retarded direction (lagging the synchronized spindle 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 the 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 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 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.

SCSI-2 Interface Product Manual).

When the target achieves synchronization, it sends a Unit

The value in byte 18 (0–FFh) is

SCSI-2 Interface

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.

20 ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D

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