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Cheetah 9LP Product Manual, Rev. C, Prefetch operation

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12 Cheetah 9LP Product Manual, Rev. C The Synchronize Cache command may be used to force the drive to write all cached write data to the medium. Upon completion of a Synchronize Cache command, all data received from previous write commands will have been written to the medium. Tables 8 show Mode default settings for the drives. 4.5.2 Prefetch operation If the Prefetch feature is enabled, data in contiguous logical blocks on the disc immediately beyond that which was requested by a Read command can be retrieved and stored in the buffer for immediate transfer from the buffer to the host on subsequent Read commands that request those logical blocks (this is true even if cache operation is disabled). Though the prefetch operation uses the buffer as a cache, finding the requested data in the buffer is a prefetch hit, not a cache operation hit. Prefetch is enabled using Mode Select page 08h, byte 12, bit 5 (Disable Read Ahead - DRA bit). DRA bit = 0 enables prefetch. Since data that is prefetched replaces data already in some buffer segment(s), the host can limit the amount of prefetch data to optimize system performance. The max prefetch field (bytes 8 and 9) limits the amount of prefetch. The drive does not use the Prefetch Ceiling field (bytes 10 and 11). During a prefetch operation, the drive crosses a cylinder boundary to fetch more data only if the Discontinuity (DISC) bit is set to one in bit 4 of byte 2 of Mode parameters page 08h. Whenever prefetch (read look-ahead) is enabled (enabled by DRA = 0), it operates under the control of ARLA (Adaptive Read Look-Ahead). If the host uses software interleave, ARLA enables prefetch of contiguous blocks from the disc when it senses that a prefetch hit will likely occur, even if two consecutive read operations were not for physically contiguous blocks of data (e.g. "software interleave"). ARLA disables prefetch when it decides that a prefetch hit will not likely occur. If the host is not using software interleave, and if two sequential read operations are not for contiguous blocks of data, ARLA disables prefetch, but as long as sequential read operations request contiguous blocks of data, ARLA keeps prefetch enabled.

Section	Page
Cheetah 9LP Family:	1
ST39102LW/LC	1
ST34502LW/LC	1
Product Manual, Volume 1	1
Cheetah 9LP Family:	3
ST39102LW/LC	3
ST34502LW/LC	3
Product Manual, Volume 1	3
Revision status summary sheet	5
Contents	7
1.0 Scope 1	7
2.0 Applicable standards and reference documentation 3	7
2.1 Standards 3	7
2.1.1 Electromagnetic compatibility 3	7
2.1.2 Electromagnetic susceptibility 3	7
2.2 Electromagnetic compliance 3	7
2.3 Reference documents 4	7
3.0 General description 5	7
3.1 Standard features 7	7
3.2 Media characteristics 7	7
3.3 Performance 7	7
3.4 Reliability 7	7
3.5 Unformatted and formatted capacities 8	7
3.6 Programmable drive capacity 8	7
3.7 Factory installed accessories 8	7
3.8 Options (factory installed) 8	7
3.9 Accessories (user installed) 8	7
4.0 Performance characteristics 9	7
4.1 Internal drive characteristics (transparent to user) 9	7
4.2 SCSI performance characteristics (visible to user) 9	7
4.2.1 Access time 9	7
4.2.2 Format command execution time (minutes) 9	7
4.2.3 Generalized performance characteristics 9	7
4.3 Start/stop time 10	7
4.4 Prefetch/multi-segmented cache control 10	7
4.5 Cache operation 10	7
4.5.1 Caching write data 11	7
4.5.2 Prefetch operation 12	7
5.0 Reliability specifications 13	7
5.1 Error rates 13	7
5.1.1 Environmental interference 13	7
5.1.2 Read errors 13	7
5.1.3 Write errors 13	7
5.1.4 Seek errors 13	7
5.2 Reliability and service 14	7
5.2.1 Mean time between failure 14	7
5.2.2 Field failure rate vs time 14	7
5.2.3 Preventive maintenance 15	7
5.2.4 Service life 15	7
5.2.5 Service philosophy 15	7
5.2.6 Service tools 15	7
5.2.7 Hot plugging Cheetah 9LP disc drives 15	7
5.2.8 S.M.A.R.T. 16	7
5.2.9 Product warranty 17	7
6.0 Physical/electrical specifications 19	7
6.1 AC power requirements 19	7
6.2 DC power requirements 19	7
6.2.1 Conducted noise immunity 20	7
6.2.2 Power sequencing 20	7
6.2.3 12 V - Current profile 20	7
6.3 Power dissipation 22	7
6.4 Environmental limits 22	7
6.4.1 Temperature 22	7
6.4.2 Relative humidity 23	8
6.4.3 Effective altitude (sea level) 24	8
6.4.4 Shock and vibration 24	8
6.4.5 Air cleanliness 26	8
6.4.6 Acoustics 26	8
6.4.7 Electromagnetic susceptibility 26	8
6.5 Mechanical specifications 27	8
7.0 Defect and error management 29	8
7.1 Drive internal defects 29	8
7.2 Drive error recovery procedures 29	8
7.3 SCSI systems errors 30	8
8.0 Installation 31	8
8.1 Drive ID/option select header 31	8
8.1.1 Notes for Figures 8, 9, and 10. 34	8
8.1.2 Function description 35	8
8.2 Drive orientation 36	8
8.3 Cooling 36	8
8.3.1 Air flow 36	8
8.4 Drive mounting 37	8
8.5 Grounding 37	8
9.0 Interface requirements 39	8
9.1 General description 39	8
9.2 SCSI interface messages supported 39	8
9.3 SCSI interface commands supported 40	8
9.3.1 Inquiry Vital Product data 43	8
9.3.2 Mode Sense data 44	8
9.4 SCSI bus conditions and miscellaneous features supported 47	8
9.5 Synchronous data transfer 48	8
9.5.1 Synchronous data transfer periods supported 48	8
9.5.2 REQ/ACK offset 48	8
9.6 Physical interface 48	8
9.6.1 DC cable and connector 48	8
9.6.2 SCSI interface physical description 50	8
9.6.3 SCSI interface cable requirements 50	8
9.6.4 Mating connectors 51	8
9.7 Electrical description 59	8
9.7.1 Multimode—SE and LVD alternatives 59	8
9.8 Terminator requirements 61	8
9.9 Terminator power 61	8
9.10 Disc drive SCSI timing 62	8
9.11 Drive activity LED 63	8
10.0 Seagate Technology support services 65	8
List of Figures	9
Figure 1. Cheetah 9LP family drive (ST39102LW shown) 1	9
Figure 2. Cheetah 9LP family drive 6	9
Figure 3. Typical Cheetah 9LP family drive +12 V current profile 21	9
Figure 4. Locations of PCBA components listed in Table 3 23	9
Figure 5. Recommended mounting 25	9
Figure 6. ST39102LW and ST34502LW mounting configuration dimensions 27	9
Figure 7. ST39102LC and ST34502LC mounting configuration dimensions 28	9
Figure 8. J6 jumper header 32	9
Figure 9. J5 jumper header (on LW models only) 33	9
Figure 10. J2 option select header 34	9
Figure 11. Air flow (suggested) 36	9
Figure 12. ST39102LW and ST34502LW drive physical interface (68-pin J1 SCSI I/O connector) 49	9
Figure 13. ST39102LC and ST34502LC drive physical interface (80-pin J1 SCSI I/O connector) 49	9
Figure 14. SCSI daisy chain interface cabling for LW drives 52	9
Figure 15. Nonshielded 68 pin SCSI device connector used on LW drives 53	9
Figure 16. Nonshielded 80 pin SCSI “SCA-2” connector, used on LC drives 54	9
Figure 17. LVD output signals 60	9
Figure 18. Typical SE-LVD alternative transmitter receiver circuits 60	9
1.0 Scope	11
Figure 1. Cheetah 9LP family drive (ST39102LW shown)	11
2.0 Applicable standards and reference documentation	13
2.1 Standards	13
2.1.1 Electromagnetic compatibility	13
2.1.2 Electromagnetic susceptibility	13
2.2 Electromagnetic compliance	13
Electromagnetic compliance for the European Union	13
Australian C-Tick	14
2.3 Reference documents	14
3.0 General description	15
Table 1: Drive model number vs. differentiating features	15
[1] See Section 9.6 for details and definitions.	15
Figure 2. Cheetah 9LP family drive	16
3.1 Standard features	17
3.2 Media characteristics	17
3.3 Performance	17
3.4 Reliability	17
3.5 Unformatted and formatted capacities	18
[1] Sector size selectable at format time. Users having the necessary equipment may modify the da...	18
[2] User available capacity depends on spare reallocation scheme selected, the number of data tra...	18
3.6 Programmable drive capacity	18
3.7 Factory installed accessories	18
3.8 Options (factory installed)	18
3.9 Accessories (user installed)	18
4.0 Performance characteristics	19
4.1 Internal drive characteristics (transparent to user)	19
4.2 SCSI performance characteristics (visible to user)	19
4.2.1 Access time [5]	19
4.2.2 Format command execution time (minutes) [1]	19
4.2.3 Generalized performance characteristics	19
Notes for Section 4.2.	20
[1] Execution time measured from receipt of the last Byte of the Command Descriptor Block (CDB) t...	20
[2] Typical access times are measured under nominal conditions of temperature, voltage, and horiz...	20
[3] Assumes no errors and no sector has been relocated.	20
[4] Assumes system ability to support the rates listed and no cable loss.	20
[5] Access time = controller overhead + average seek time. Access to data = controller overhead +...	20
4.3 Start/stop time	20
4.4 Prefetch/multi-segmented cache control	20
4.5 Cache operation	20
1. Drive transfers to the initiator the first LB requested plus all subsequent contiguous LBs tha...	21
2. When the requested LB is reached that is not in any cache segment, the drive fetches it and an...	21
3. If the prefetch feature is enabled, refer to Section 4.5.2 for operation from this point.	21
1. The drive fetches the requested LBs from the disc and transfers them into a segment, and from ...	21
2. If the prefetch feature is enabled, refer to Section 4.5.2 for operation from this point.	21
4.5.1 Caching write data	21
4.5.2 Prefetch operation	22
5.0 Reliability specifications	23
Note.	23
[1] Error rate specified with automatic retries and data correction with ECC enabled and all flaw...	23
5.1 Error rates	23
5.1.1 Environmental interference	23
5.1.2 Read errors	23
5.1.3 Write errors	23
5.1.4 Seek errors	23
5.2 Reliability and service	24
5.2.1 Mean time between failure	24
5.2.2 Field failure rate vs time	24
5.2.3 Preventive maintenance	25
5.2.4 Service life	25
5.2.5 Service philosophy	25
5.2.6 Service tools	25
5.2.7 Hot plugging Cheetah 9LP disc drives	25
5.2.8 S.M.A.R.T.	26
Controlling S.M.A.R.T.	26
Performance impact	26
Reporting control	26
Determining rate	26
Predictive failures	27
5.2.9 Product warranty	27
Shipping	27
Product repair and return information	27
6.0 Physical/electrical specifications	29
6.1 AC power requirements	29
6.2 DC power requirements	29
Table 2: DC power requirements	29
[1] Measured with average reading DC ammeter. Instantaneous +12 V current peaks will exceed these...	29
[2] For +12 V, a –10% tolerance is permissible during initial start of spindle, and must return t...	29
[3] See +12 V current profile in Figure 3.	29
[4] This condition occurs when the Motor Start Option is enabled and the drive has not yet receiv...	29
[5] See Section 6.2.1 “Conducted Noise Immunity.” Specified voltage tolerance is inclusive of rip...	29
[6] At power up, the motor current regulator limits the 12 volt current to an average of less tha...	29
[7] Operating condition is defined as a third stroke seek at OD and read one track. Command issue...	29
[8] No terminator power.	29
[9] During idle, the drive heads are relocated every 60 seconds to a random location within the b...	29
1. Minimum current loading for each supply voltage is not less than 2% of the maximum operating c...	29
2. The +5 and +12 volt supplies shall employ separate ground returns.	29
3. Where power is provided to multiple drives from a common supply, careful consideration for ind...	30
4. Parameters, other than spindle start, are measured after a 10-minute warm up.	30
6.2.1 Conducted noise immunity	30
6.2.2 Power sequencing	30
6.2.3 12 V - Current profile	30
Figure 3. Typical Cheetah 9LP family drive +12 V current profile	31
6.3 Power dissipation	32
ST39102	32
ST34502	32
6.4 Environmental limits	32
6.4.1 Temperature	32
a. Operating	32
Table 3: PCBA and HDA temperatures	32
Notes.	33
[1] Section 8.3.1 describes the air-flow patterns used when generating the 1 million hours MTBF g...	33
[2] Measure HDA temp at point labeled “HDA” on Figure 4.	33
[3] PCB mounted integrated circuit case.	33
b. Non-operating	33
Figure 4. Locations of PCBA components listed in Table 3	33
6.4.2 Relative humidity	33
a. Operating	33
b. Non-operating	33
6.4.3 Effective altitude (sea level)	34
a. Operating	34
b. Non-operating	34
6.4.4 Shock and vibration	34
6.4.4.1 Shock	34
a. Operating—normal	34
b. Operating—abnormal	34
c. Non-operating	34
d. Packaged	34
Figure 5. Recommended mounting	35
6.4.4.2 Vibration	36
a. Operating - normal	36
b. Operating - abnormal	36
c. Non-operating	36
6.4.5 Air cleanliness	36
6.4.6 Acoustics	36
6.4.7 Electromagnetic susceptibility	36
6.5 Mechanical specifications	37
Figure 6. ST39102LW and ST34502LW mounting configuration dimensions	37
Figure 7. ST39102LC and ST34502LC mounting configuration dimensions	38
7.0 Defect and error management	39
7.1 Drive internal defects	39
7.2 Drive error recovery procedures	39
Table 4: Read and write retry count maximum recovery times [1]	40
[1] These values are subject to change. Setting these retry counts to a value below the default s...	40
7.3 SCSI systems errors	40
8.0 Installation	41
Configure drive options	41
Formatting	41
8.1 Drive ID/option select header	41
Figure 8. J6 jumper header	42
Figure 9. J5 jumper header (on LW models only)	43
Figure 10. J2 option select header	44
8.1.1 Notes for Figures 8, 9, and 10.	44
[1] Notes explaining the functions of the various jumpers on jumper header connectors J2, J5, and...	44
[2] These signals are also on 80-pin J1 I/O connector. See Tables 15 and 16.	44
[3] Voltage supplied by the drive.	44
8.1.2 Function description	45
8.2 Drive orientation	46
8.3 Cooling	46
8.3.1 Air flow	46
Figure 11. Air flow (suggested)	46
8.4 Drive mounting	47
8.5 Grounding	47
9.0 Interface requirements	49
9.1 General description	49
9.2 SCSI interface messages supported	49
Table 5: SCSI messages supported by Cheetah 9LP family drives	49
Notes.	49
[1] Extended messages (see the SCSI Interface Product Manual, part number 77738479).	49
9.3 SCSI interface commands supported	50
Table 6: Commands supported by Cheetah 9LP family drive (Continued)	50
[1] The drive can format to any even number of bytes per sector from 180 to 4,096	52
[2] Tables 8 show how individual bits are set and which are changeable by the host.	52
[3] WARNING: A power loss during flash programming can result in firmware corruption. This usuall...	52
Table 7: Cheetah 9LP family drive Standard Inquiry data	53
9.3.1 Inquiry Vital Product data	53
9.3.2 Mode Sense data	54
Table 8: Mode sense data, ST39102 values (SCSI-2/3 implementation)	55
[1] Though byte 12, bit 7 (A0) is shown as changeable, the FSW function governed by that bit is n...	55
Table 9: Mode sense data, ST34502 values (SCSI-2/3 implementation)	56
[1] Though byte 12, bit 7 (A0) is shown as changeable, the FSW function governed by that bit is n...	56
9.4 SCSI bus conditions and miscellaneous features supported	57
Table 10: SCSI bus conditions and other miscellaneous features	57
9.5 Synchronous data transfer	58
9.5.1 Synchronous data transfer periods supported	58
Table 11: Synchronous data transfer periods	58
9.5.2 REQ/ACK offset	58
9.6 Physical interface	58
9.6.1 DC cable and connector	58
Figure 12. ST39102LW and ST34502LW drive physical interface (68-pin J1 SCSI I/O connector)	59
Figure 13. ST39102LC and ST34502LC drive physical interface (80-pin J1 SCSI I/O connector)	59
9.6.2 SCSI interface physical description	60
Table 12: Interface transfer rates supported	60
9.6.3 SCSI interface cable requirements	60
The characteristics of cables used to connect SCSI-3 parallel interface devices are discussed in ...	60
To minimize discontinuances and signal reflections, cables of different impedances should not be ...	61
ST39102LC and ST34502LC:	61
9.6.4 Mating connectors	61
9.6.4.1 Mating connectors for ST39102LW and ST34502LW drives	61
[1] See Figure 14.	61
9.6.4.2 Mating connectors for ST39102LC and ST34502LC drives	61
[1] Closed end type 68-pin connector used. Terminators enabled.	62
[2] Open end type (in-line application) connector used.	62
[3] Host need not be on the end of the daisy-chain. Another device can be on the end with the ter...	62
[4] Total interface cable length must not exceed that specified in ANSI document X3T10/1142D (inc...	62
[5] SCSI ID7 has highest arbitration priority, then ID15 to ID8 (ID 8 very lowest).	62
[6] Last drive on the daisy chain.	62
[7] Open-end type 68-pin connector used. If end device, use external terminator and closed-end ty...	62
Figure 14. SCSI daisy chain interface cabling for LW drives	62
Figure 15. Nonshielded 68 pin SCSI device connector used on LW drives	63
Figure 16. Nonshielded 80 pin SCSI “SCA-2” connector, used on LC drives	64
Table 13: LW 68-conductor single-ended (SE) P cable signal/pin assignments [13]	65
Table 14: LW 68-conductor LVD P cable signal/pin assignments [13]	66
Table 15: LC 80-pin single-ended (SE) I/O connector pin assignments [13]	67
Table 16: LC 80-pin single-ended (LVD) I/O connector pin assignments [13]	68
Notes [] for Tables 13 through 16.	69
[1] See Section 9.6.4.1 for detailed electrical characteristics of these signals.	69
[2] The conductor number refers to the conductor position when using 0.025-inch (0.635 mm) center...	69
[3] Connector contacts are on 0.050 inch (1.27 mm) centers.	69
[4] Front panel LED signal; indicates drive activity for host front panel hard drive activity ind...	69
[5] Asserted by host to enable Motor Start option (enables starting motor via SCSI bus command).	69
[6] Asserted by host to enable Delayed Motor Start option (motor starts at power on or after a de...	69
[7] Binary code on A3, A2, A1 and A0 asserted by host to set up SCSI bus ID in drive.	69
[8] GND provides a means for differential devices to detect the presence of a single ended device...	69
[9] Signals [4] through [7] are used in place of installing jumpers and cables on option select c...	69
[10] “NC” means no connection.	69
[11] The conductor number refers to the conductor position (right to left in Figure 14) when usin...	69
[12] Connector contacts are on 0.100 inch (2.54 mm) centers.	69
[13] 8 bit devices which are connected to the 16 data bit LVD I/O shall leave the following signa...	69
9.7 Electrical description	69
9.7.1 Multimode—SE and LVD alternatives	69
Multimode signals	69
Output characteristics	69
Figure 17. LVD output signals	70
Input characteristics	70
Figure 18. Typical SE-LVD alternative transmitter receiver circuits	70
9.7.1.1 Single-ended drivers/receivers	71
Table 17: Cable characteristics for single-ended circuits	71
9.7.1.2 Low voltage differential I/O circuits	71
9.7.1.3 General cable characteristics	71
9.8 Terminator requirements	71
9.9 Terminator power	71
LW drives	71
LC drives	71
9.10 Disc drive SCSI timing	72
Table 18: Disc drive SCSI timing (Continued)	72
Notes.	73
[1] See the SCSI Interface Product Manual, part number 77738479, Section 4.5	73
[2] Maximum SCSI asynchronous interface transfer rate is given in Section 4.2.3 of this manual.	73
[3] Synchronous Transfer Period is determined by negotiations between an Initiator and a Drive. T...	73
9.11 Drive activity LED	73
Table 19: Drive activity LED status	73
10.0 Seagate Technology support services	75
Index	79
Symbols	79
Numerics	79
A	79
B	79
C	79
D	79
E	80
F	80
G	80
H	80
I	81
J	81
L	81
M	81
N	81
O	81
P	82
R	82
S	82
T	83
U	83
V	83
W	83

Match case Limit results 1 per page

Cheetah 9LP Product Manual, Rev. C

The Synchronize Cache command may be used to force the drive to write all cached write data to the medium.

Upon completion of a Synchronize Cache command, all data received from previous write commands will have

been written to the medium.

Tables 8 show Mode default settings for the drives.

4.5.2

Prefetch operation

If the Prefetch feature is enabled, data in contiguous logical blocks on the disc immediately beyond that which

was requested by a Read command can be retrieved and stored in the buffer for immediate transfer from the

buffer to the host on subsequent Read commands that request those logical blocks (this is true even if cache

operation is disabled). Though the prefetch operation uses the buffer as a cache, finding the requested data in

the buffer is a prefetch hit, not a cache operation hit. Prefetch is enabled using Mode Select page 08h, byte 12,

bit 5 (Disable Read Ahead - DRA bit). DRA bit = 0 enables prefetch. Since data that is prefetched replaces data

already in some buffer segment(s), the host can limit the amount of prefetch data to optimize system perfor-

mance. The max prefetch field (bytes 8 and 9) limits the amount of prefetch. The drive does not use the

Prefetch Ceiling field (bytes 10 and 11).

During a prefetch operation, the drive crosses a cylinder boundary to fetch more data only if the Discontinuity

(DISC) bit is set to one in bit 4 of byte 2 of Mode parameters page 08h.

Whenever prefetch (read look-ahead) is enabled (enabled by DRA = 0), it operates under the control of ARLA

(Adaptive Read Look-Ahead). If the host uses software interleave, ARLA enables prefetch of contiguous blocks

from the disc when it senses that a prefetch hit will likely occur, even if two consecutive read operations were

not for physically contiguous blocks of data (e.g. “software interleave”). ARLA disables prefetch when it decides

that a prefetch hit will not likely occur. If the host is not using software interleave, and if two sequential read

operations are not for contiguous blocks of data, ARLA disables prefetch, but as long as sequential read oper-

ations request contiguous blocks of data, ARLA keeps prefetch enabled.