Seagate ST336854FC, ST3146954FC, ST373554FC User Manual

Cheetah 15K.4 FC
ST3146954FC
ST373554FC
ST336854FC
Cheetah 15K.4 FC
ST3146954FC
ST373554FC
ST336854FC
©2005, 2006, Seagate Technology LLC All rights reserved
Publication number: 100366896, Rev. B
March 2006
Seagate, Seagate Technology, and the Seagate logo are registered trademarks of Seagate Technology LLC. SeaTools, SeaFONE, SeaBOARD, and SeaTDD are either registered trademarks or trademarks of Seagate Technology LLC. 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 of Seagate
Technology LLC.
Revision status summary sheet
Revision Date Sheets Affected
Rev. A 07/15/05 All. Rev. B (Draft 1) 03/17/06 Pages 25 and 26.
Contents
1.0 Scope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2.0 Applicable standards and reference documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1 Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1.1 Electromagnetic compatibility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1.2 Electromagnetic compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2 Reference documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.0 General description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1 Standard features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2 Media description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.3 Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.4 Reliability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.5 Formatted capacities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.5.1 Programmable drive capacity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.6 Factory-installed accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.7 Factory-installed options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.8 User-installed accessories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.0 Performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.1 Internal drive characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.2 Seek performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.2.1 Access time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.2.2 Format command execution time (minutes) . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.2.3 General performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.3 Start/stop time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.4 Prefetch/multi-segmented cache control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.5 Cache operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.5.1 Caching write data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.5.2 Prefetch operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.5.3 Optimizing cache performance for desktop and server applications . . . . . . . . . 14
5.0 Reliability specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.1 Error rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.1.1 Recoverable Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.1.2 Unrecoverable Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.1.3 Seek errors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.1.4 Interface errors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.2 Reliability and service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.2.1 Mean time between failure (MTBF) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.2.2 Preventive maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.2.3 Hot plugging the drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.2.4 S.M.A.R.T. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.2.5 Thermal monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.2.6 Drive Self Test (DST) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.2.7 Product warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
6.0 Physical/electrical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
6.1 AC power requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
6.2 DC power requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
6.2.1 Conducted noise immunity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.2.2 Power sequencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.2.3 Current profiles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.3 Power dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.4 Environmental limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Cheetah 15K.4 FC Product Manual, Rev. B i
6.4.1 Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
6.4.2 Relative humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
6.4.3 Effective altitude (sea level) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
6.4.4 Shock and vibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
6.4.5 Air cleanliness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
6.4.6 Acoustics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
6.4.7 Electromagnetic susceptibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
6.5 Mechanical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
7.0 Defect and error management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
7.1 Drive internal defects/errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
7.2 Drive error recovery procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
7.3 FC-AL system errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
7.4 Background Media Scan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
7.4.1 Media Pre-Scan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
8.0 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
8.1 Drive ID/option selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
8.2 LED connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
8.2.1 J6 connector requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
8.3 Drive orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
8.4 Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
8.5 Drive mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
8.6 Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
9.0 Interface requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
9.1 FC-AL features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
9.1.1 Fibre Channel link service frames . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
9.1.2 Fibre Channel task management functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
9.1.3 Fibre Channel task management responses . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
9.1.4 Fibre Channel port login . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
9.1.5 Fibre Channel port login accept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
9.1.6 Fibre Channel Process Login . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
9.1.7 Fibre Channel Process Login Accept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
9.1.8 Fibre Channel fabric login. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
9.1.9 Fibre Channel fabric accept login . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
9.1.10 Fibre Channel Arbitrated Loop options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
9.2 Dual port support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
9.3 SCSI commands supported . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
9.3.1 Inquiry data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
9.3.2 Mode Sense data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
9.4 Miscellaneous operating features and conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
9.5 FC-AL physical interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
9.5.1 Physical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
9.5.2 Connector requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
9.5.3 Electrical description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
9.5.4 Pin descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
9.5.5 FC-AL transmitters and receivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
9.5.6 Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
9.5.7 Fault LED Out. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
9.5.8 Active LED Out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
9.5.9 Enable port bypass signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
9.5.10 Motor start controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
9.5.11 SEL_6 through SEL_0 ID lines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
9.5.12 Device control codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
9.6 Signal characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
ii Cheetah 15K.4 FC Product Manual, Rev. B
9.6.1 TTL input characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
9.6.2 LED driver signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
9.6.3 FC Differential output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
9.6.4 FC Differential input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
10.0 Seagate Technology support services. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Cheetah 15K.4 FC Product Manual, Rev. B iii
iv Cheetah 15K.4 FC Product Manual, Rev. B
List of Figures
Figure 1. Cheetah 15K.4 FC family disc drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Figure 2. Typical ST3146954FC drive, 2 Gbit, +12V current profile . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Figure 3. Typical ST3146954FC drive, 2 Gbit, +5V current profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Figure 4. Typical ST373554FC drive +12V current profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 5. Typical ST373554FC drive +5V current profile. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 6. Typical ST336854FC drive +12V current profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Figure 7. Typical ST336854FC drive +5V current profile. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Figure 8. ST3146954FC DC current and power vs. input/output operations per second . . . . . . . . . . . 31
Figure 9. ST373554FC DC current and power vs. input/output operations per second . . . . . . . . . . . . 32
Figure 10. ST336854FC DC current and power vs. input/output operations per second . . . . . . . . . . . . 33
Figure 11. Locations of the HDA temperature check point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Figure 12. Recommended mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Figure 13. Mounting configuration dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Figure 14. Physical interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Figure 15. LED indicator connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Figure 16. Air flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Figure 17. Physical interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Figure 18. Port bypass circuit physical interconnect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Figure 19. FC-AL SCA device connector dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Figure 20. J6 connector dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Figure 21. FC-AL transmitters and receivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Figure 22. Transmit eye diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Figure 23. Receive eye diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Cheetah 15K.4 FC Product Manual, Rev. B v

1.0 Scope

This manual describes Seagate Technology® LLC, Cheetah® 15K.4 FC (Fibre Channel) disc drives.
Cheetah 15K.4 FC drives support the Fibre Channel Arbitrated Loop and SCSI Fibre Channel Protocol specifi-
cations to the extent described in this manual. The Fibre Channel Interface Manual (part number 77767496)
describes the general Fibre Channel Arbitrated Loop characteristics of this and other Seagate Fibre Channel
drives.
Figure 1. Cheetah 15K.4 FC family disc drive
Cheetah 15K.4 FC Product Manual, Rev. B 1
2 Cheetah 15K.4 FC Product Manual, Rev. B

2.0 Applicable standards and reference documentation

The drive has been developed as a system peripheral to the highest standards of design and construction. The
drive depends upon its host equipment to provide adequate power and environment in order to achieve opti
mum performance and compliance with applicable industry and governmental regulations. Special attention
must be given in the areas of safety, power distribution, shielding, audible noise control, and temperature regu
lation. In particular, the drive must be securely mounted in order to guarantee the specified performance char-
acteristics. Mounting by bottom holes must meet the requirements of Section 8.5.

2.1 Standards

The Cheetah 15K.4 FC family complies with Seagate standards as noted in the appropriate sections of this
manual and the Seagate Fibre Channel Interface Manual, part number 77767496.
The Cheetah 15K.4 FC disc drive is a UL recognized component per UL1950, CSA certified to CAN/CSA
C22.2 No. 950-95, and VDE certified to VDE 0805 and EN60950.

2.1.1 Electromagnetic compatibility

The drive, as delivered, is designed for system integration and installation into a suitable enclosure prior to
use. As such the drive is supplied as a subassembly and is not subject to Subpart B of Part 15 of the FCC
Rules and Regulations nor the Radio Interference Regulations of the Canadian Department of Communica
tions.
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The design characteristics of the drive serve to minimize radiation when installed in an enclosure that provides
reasonable shielding. As such, the drive is capable of meeting the Class B limits of the FCC Rules and Regula
tions of the Canadian Department of Communications when properly packaged. However, it is the user’s
responsibility to assure that the drive meets the appropriate EMI requirements in their system. Shielded I/O
cables may be required if the enclosure does not provide adequate shielding. If the I/O cables are external to
the enclosure, shielded cables should be used, with the shields grounded to the enclosure and to the host con
troller.
2.1.1.1 Electromagnetic susceptibility
As a component assembly, the drive is not required to meet any susceptibility performance requirements. It is
the responsibility of those integrating the drive within their systems to perform those tests required and design
their system to ensure that equipment operating in the same system as the drive or external to the system
does not adversely affect the performance of the drive. See Table
2, DC power requirements.
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Cheetah 15K.4 FC Product Manual, Rev. B 3

2.1.2 Electromagnetic compliance

Seagate uses an independent laboratory to confirm compliance with the directives/standards for CE Marking and C-Tick Marking. The drive was tested in a representative system for typical applications. The selected sys tem represents the most popular characteristics for test platforms. The system configurations include:
• Typical current use microprocessor
• 3.5-inch floppy disc drive
• Keyboard
• Monitor/display
• Printer
• External modem
•Mouse
Although the test system with this Seagate model complies with the directives/standards, we cannot guarantee that all systems will comply. The computer manufacturer or system integrator shall confirm EMC compliance and provide the appropriate marking for their product.
Electromagnetic compliance for the European Union
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.
Australian C-Tick
-
If this model has the C-Tick Marking it complies with the Australia/New Zealand Standard AS/NZS3548 1995 and meets the Electromagnetic Compatibility (EMC) Framework requirements of Australia’s Spectrum Man agement Agency (SMA).
Korean MIC
If this model has the Korean Ministry of Information and Communication (MIC) logo, it complies with paragraph 1 of Article 11 of the Electromagnetic Compatibility (EMC) Control Regulation and meets the Electromagnetic Compatibility Framework requirements of the Radio Research Laboratory (RRL) Ministry of Information and Communication Republic of Korea.
Taiwanese BSMI
If this model has the Chinese National Standard (CNS) 13438 marking, it complies with Chinese National Stan­dard (CNS) 13438 and meets the Electromagnetic Compatibility (EMC) Framework requirements of the Tai­wanese Bureau of Standards, Metrology, and Inspection (BSMI).
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4 Cheetah 15K.4 FC Product Manual, Rev. B

2.2 Reference documents

Cheetah 15K.4 FC Installation Guide Seagate part number: 100366897
Fibre Channel Interface Manual Seagate part number: 77767496
ANSI Fibre Channel Documents
Project T11/1619-D FC-FS-2 Fibre Channel - Framing and Signaling
Project T11/1506-D FC-PI-2 Fibre Channel - PHYSICAL INTERFACES - 2
ANSI INCITS 332-1999 FC.AL-2 Arbitrated Loop 2
ANSI INCITS 332-1999/AM1-2003 FC.AL-2 Arbitrated Loop 2 Amendment
ANSI INCITS 350-2003 FCP-2 Fibre Channel Protocol 2
NCITS TR-19 Private Loop SCSI Direct Attach (PLDA)
NCITS TR-20 Fabric Loop Attachment (FC-FLA)
SFF-8045 Specification for 40-pin SCA-2 Connector with Parallel Selection
SFF-8067 Specification for 40-pin SCA-2 Connector with Bidirectional
Enclosure Services Interface
ANSI Small Computer System Interface (SCSI) Documents
ISO/IEC 14776-xxx SCSI Architecure Model-3 (SAM-3) Standard (T10/1561-D)
ISO/IEC 14776-xxx SCSI Primary Commands-3 (SPC-3) Standard (T10/1416-D)
ISO/IEC 14776-xxx SCSI Block Commands-2 (SBC-2) Standard (T10/1417-D)
Specification for Acoustic Test Requirement and Procedures
Seagate part number: 30553-001
Package Test Specification Seagate P/N 30190-001 (under 100 lb.)
Package Test Specification Seagate P/N 30191-001 (over 100 lb.)
In case of conflict between this document and any referenced document, this document takes precedence.
Cheetah 15K.4 FC Product Manual, Rev. B 5
6 Cheetah 15K.4 FC Product Manual, Rev. B

3.0 General description

Cheetah 15K.4 FC drives combine giant magnetoresistive (GMR) heads, partial response/maximum likelihood
(PRML) read channel electronics, embedded servo technology, and a Fibre Channel interface to provide high
performance, high capacity data storage for a variety of systems including engineering workstations, network
servers, mainframes, and supercomputers. Cheetah 15K.4 FC drives also support 2-Gbit Fibre Channel which
can transfer data at up to 200 Mbytes per second and 400 Mbytes per second in dual-loop configurations.
ST373453, ST336753, and ST318453 models also support 4-Gbit Fibre Channel which can transfer data at up
to 400 Mbytes per second and 800 Mbytes per second in dual-loop configurations.
Cheetah 15K.4 FC drives support the Fibre Channel Arbitrated Loop (FC-AL) and SCSI Fibre Channel Proto-
col as described in the ANSI specifications, this document, and the Fibre Channel Interface Manual (part num-
ber 77767496) which describes the general interface characteristics of this drive. Cheetah 15K.4 FC drives are
classified as intelligent peripherals and provide level 2 conformance (highest level) with the ANSI SCSI-1 stan
dard.
Never disassemble the HDA and do not attempt to service items in the sealed enclosure (heads, media, actu-
ator, etc.) as this requires special facilities. The drive does not contain user-replaceable parts. Opening the
HDA for any reason voids your warranty.
Cheetah 15K.4 FC 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 heads automatically go to the land
ing zone when power is removed from the drive.
An automatic shipping lock prevents potential damage to the heads and discs that results from movement dur-
ing shipping and handling. The shipping lock disengages and the head load process begins when power is
applied to the drive.
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The drives also use a high-performance actuator assembly with a low-inertia, balanced, patented, straight arm
design that provides excellent performance with minimal power dissipation.
Cheetah 15K.4 FC Product Manual, Rev. B 7

3.1 Standard features

Cheetah 15K.4 FC drives have the following standard features:
• 4-Gbit Fibre Channel interface. For 2 or 4 gigabit operation, the block size must be divisable by 8.
• Integrated dual port FC-AL controller
• Concurrent dual port transfers
• Support for FC arbitrated loop, private and public attachment
• Differential copper FC drivers and receivers
• Downloadable firmware using the FC-AL interface
• Supports SCSI enclosure services via interface connector
• 128-deep task set (queue)
• Supports up to 32 initiators
• Drive selection ID and configuration options are set on the FC-AL backpanel or through interface com­mands. Jumpers are not used on the drive.
• Supports SCSI Enclosure Services through the interface connector
• Fibre Channel worldwide name uniquely identifies the drive and each port
• User-selectable logical block size (512 to 528 bytes per logical block). For 2 or 4 gigabit operation, the block size must be divisable by 8.
• Selectable frame sizes from 256 to 2,112 bytes
• Industry standard 3.5-inch low profile form factor dimensions
• Programmable logical block reallocation scheme
• Flawed logical block reallocation at format time
• Programmable auto write and read reallocation
• Reed-Solomon error correction code
• Sealed head and disc assembly (HDA)
• No preventive maintenance or adjustments required
• Dedicated head landing zone
• Automatic shipping lock
• 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
• 16,384 Kbyte data buffer (see Section 4.5).
• Embedded servo design
• Reallocation of defects on command (Post Format)
• Fibre Channel interface transports SCSI protocol

3.2 Media description

The media used on the drive has an aluminum substrate coated with a thin film magnetic material, overcoated with a proprietary protective layer for improved durability and environmental protection.
8 Cheetah 15K.4 FC Product Manual, Rev. B

3.3 Performance

• Programmable multi-segmentable cache buffer
• 200 Mbytes/sec maximum instantaneous data transfers per port
• 15k RPM spindle; average latency = 2.0 msec
• Command queuing of up to 128 commands
• Background processing of queue
• Supports start and stop commands (spindle stops spinning)
• Adaptive seek velocity; improved seek performance

3.4 Reliability

• 1,400,000 hour MTBF
• Increased LSI circuitry integration
• Self-Monitoring Analysis and Reporting Technology (S.M.A.R.T.)
• Dithering

3.5 Formatted capacities

Standard OEM models are formatted to 512 bytes per block. The sector size is selectable at format time. Users having the necessary equipment may modify the data block size before issuing a format command and obtain different formatted capacities than those listed.
To provide a stable target capacity environment and at the same time provide users with flexibility if they choose, Seagate recommends product planning in one of two modes:
1. Seagate designs specify capacity points at certain sector sizes that Seagate guarantees current and future products will meet. We recommend customers use this capacity in their project planning, as it ensures a stable operating point with backward and forward compatibility from generation to generation. The current guaranteed operating points for this product are:
ST336854FC ST373554FC ST3146954FC
Sector Size
Decimal Hex Decimal Hex Decimal Hex
512 71,687,372 445DCCC 143,374,744 88BB998 286,749,488 11177330
514 70,512,692 433F034 141,025,384 867E068 282,050,768 10CFC0D0
520 70,197,546 42F212A 140,395,092 85E4254 280,790,184 10BC84A8
522 68,914,176 41B8C00 139,463,602 8500BB2 279,041,740 10A1D6CC
524 68,766,592 4194B80 137,577,184 83342E0 275,154,368 106685C0
2. Seagate drives also may be used at the maximum available capacity at a given sector size, but the excess capacity above the guaranteed level will vary between 10K and 15K families and from generation to gener ation, depending on how each sector size actually formats out for zone frequencies and splits over servo bursts. This added capacity potential may range from 0.1 to 1.3 percent above the guaranteed capacities listed above. Using the drives in this manner gives the absolute maximum capacity potential, but the user must determine if the extra capacity potential is useful, or whether their assurance of backward and for ward compatibility takes precedence.

3.5.1 Programmable drive capacity

Using the Mode Select command, the drive can change its capacity to something less than maximum. See the Mode Select Parameter List table in the SCSI Interface Product Manual. Refer to the Parameter list block descriptor number of blocks field. A value of zero in the number of blocks field indicates that the drive shall not
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Cheetah 15K.4 FC Product Manual, Rev. B 9
change the capacity it is currently formatted to have. A number in the number of blocks field that is less than the maximum number of LBAs changes the total drive capacity to the value in the block descriptor number of blocks field. A value greater than the maximum number of LBAs is rounded down to the maximum capacity.

3.6 Factory-installed accessories

OEM standard drives are shipped with the Cheetah 15K.4 FC Installation Guide (part number 100366897) and the Safety and Regulatory Agency Specifications, part number 75789512 (unless otherwise specified).

3.7 Factory-installed options

You may order the following items which are incorporated at the manufacturing facility during production or packaged before shipping. Some of the options available are (not an exhaustive list of possible options):
• Other capacities can be ordered depending on sparing scheme and sector size requested.
• 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.
•The Cheetah 15K.4 FC Installation Guide, part number 100366897, is usually included with each standard OEM drive shipped, but extra copies may be ordered.
•The Safety and Regulatory Agency Specifications, part number 75789512, is usually included with each standard OEM drive shipped, but extra copies may be ordered.

3.8 User-installed accessories

The following accessories are available. All kits may be installed in the field.
• Evaluation kit, Seagate part number 100364396. This kit provides an adapter card (“T-card”) to allow cable connections for two FC ports and DC power. You may purchase this evaluation kit from channel distributors or your Seagate representative.
• Single-unit shipping pack.
10 Cheetah 15K.4 FC Product Manual, Rev. B

4.0 Performance characteristics

This section provides detailed information concerning performance-related characteristics and features of Cheetah 15K.4 FC drives.

4.1 Internal drive characteristics

ST3146954FC ST373554FC ST336854FC Drive capacity 146.8 73.4 36.7 Gbytes (formatted, rounded off value) Read/write data heads 8 4 2 Bytes per track 471,916 471,916 471,916 Bytes (average, rounded off values) Bytes per surface 18,351 18,351 18,351 Mbytes (unformatted, rounded off value) Tracks per surface (total) 50,864 50,864 50,864 Tracks (user accessible) Tracks per inch 85,000 85,000 85,000 TPI Peak bits per inch 628 628 628 KBPI Internal data rate 685-1,142 685-1,142 685-1,142 Mbits/sec (variable with zone) Disc rotation speed 15k 15k 15k rpm Avg rotational latency 2.0 2.0 2.0 msec

4.2 Seek performance characteristics

See Section 9.5, "FC-AL physical interface" on page 64 and the Fibre Channel Interface Manual (part number
77767496) for additional timing details.

4.2.1 Access time

Not including controller overhead
Read Write
Average Typical 3.5 4.0
Single track Typical 0.27 0.45
Full stroke Typical 7.4 7.9
1. Typical access times are measured under nominal conditions of temperature, voltage,
and horizontal orientation as measured on a representative sample of drives.
2. Access to data = access time + latency time.
1,2
(msec)
Cheetah 15K.4 FC Product Manual, Rev. B 11

4.2.2 Format command execution time (minutes)

ST3146954FC ST373554FC ST336854FC
Maximum (with verify)
Maximum (without verify)
90 60 30
45 30 15

4.2.3 General performance characteristics

Data buffer to/from disc media (one 512-byte logical block)*
Minimum 685 Mbits/sec
Maximum 1,142 Mbits/sec
Fibre Channel Interface maximum instantaneous transfer rate 200 Mbytes/sec* per port
Logical block sizes
Default is 512-byte data blocks Variable 512 to 704 bytes per sector in even number of bytes per sector. If n (number of bytes per sector) is odd, then n-1 will be used.
Read/write consecutive sectors on a track Yes
Flaw reallocation performance impact (for flaws reallocated at format time using the spare sectors per sparing zone reallocation scheme.)
Average rotational latency 2.0 msec
*Assumes no errors and no relocated logical blocks. Rate measured from the start of the first logical block transfer to or from the host.
(dual port = 400 Mbytes/sec*)
Negligible

4.3 Start/stop time

If the Motor Start option is disabled, the drive becomes ready within 20 seconds after DC power is applied. If a recoverable error condition is detected during the start sequence, the drive executes a recovery procedure and the time to become ready may exceed 20 seconds. Stop time is 30 seconds (maximum) from removal of DC power.
If the Motor Start option is enabled, the internal controller accepts the commands listed in the Fibre Channel Interface Manual less than 3 seconds after DC power has been applied. After the Motor Start command has been received, the drive becomes ready for normal operations within 20 seconds (excluding the error recovery procedure). The Motor Start command can also be used to command the drive to stop the spindle.
There is no power control switch on the drive.

4.4 Prefetch/multi-segmented cache control

The drive provides a prefetch (read look-ahead) and multi-segmented cache control algorithms that in many cases can enhance system performance. Cache refers to the drive buffer storage space when it is used in cache operations. To select this feature, the host sends the Mode Select command with the proper values in
12 Cheetah 15K.4 FC Product Manual, Rev. B
the applicable bytes in page 08h. Prefetch and cache operations are independent features from the standpoint that each is enabled and disabled independently using the Mode Select command; however, in actual opera tion, the prefetch feature overlaps cache operation somewhat as described in sections 4.5.1 and 4.5.2.
All default cache and prefetch mode parameter values (Mode Page 08h) for standard OEM versions of this drive family are given in Table
18.

4.5 Cache operation

Note. Refer to the Fibre Channel Interface Manual for more detail concerning the cache bits.
Of the 16,384 kbytes physical buffer space in the drive, approximately 14,218 kbytes can be used as a cache. Cache segmenting is adjusted dynamically by the disk drive hardware according to the workload being experi enced by the drive. The drive is capable of dynamically-adjusting up to 256 segments. The number and sizes of segments are not user-defined.
The drive keeps track of the logical block addresses of the data stored in each segment of the buffer. If the cache is enabled (see RCD bit in the Fibre Channel Interface Manual command is retrieved from the buffer, if possible, before any disc access is initiated. If cache operation is not enabled, the buffer is still used, but only as circular buffer segments during disc medium read operations (dis regarding Prefetch operation for the moment). That is, the drive does not check in the buffer segments for the requested read data, but goes directly to the medium to retrieve it. The retrieved data merely passes through some buffer segment on the way to the host. On a cache miss, all data transfers to the host are in accordance with buffer-full ratio rules. On a cache hit, the drive ignores the buffer-full ratio rules. See the explanation pro vided with the information about Mode Page 02h (disconnect/reconnect control) in the Fibre Channel Interface
Manual.
), data requested by the host with a read
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The following is a simplified description of the prefetch/cache operation:
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.
2. When a requested logical block is reached that is not in any cache 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 host in accordance with the Mode Select Disconnect/Reconnect parameters, page 02h.
3. If the prefetch feature is enabled, refer to section 4.5.2 for operation from this point.
Case B—A Read command requests data, and the first logical block 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, and then
from there to the host in accordance with the Mode Select Disconnect/Reconnect parameters, page 02h.
2. If the prefetch feature is enabled, refer to section 4.5.2 for operation from this point.
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 08h. Default is zero for bit 4.
Each cache segment is actually a self-contained circular buffer whose length is an integer number of logical blocks. The sizes of the segments are determined by the drive’s analysis of the current workload.
Note. The size of each segment is not reported by Mode Sense command page 08h, bytes 14 and 15.
The value 0XFFFF is always reported regardless of the actual size of the segment. Sending a size specification using the Mode Select command (bytes 14 and 15) does not set up a new segment size. If the STRICT bit in Mode page 00h (byte 2, bit 1) is set to one, the drive responds as it does for any attempt to change an unchangeable parameter.
Cheetah 15K.4 FC Product Manual, Rev. B 13

4.5.1 Caching write data

Write caching is a write operation by the drive that makes use of a drive buffer storage area where the data to be written to the medium is stored while the drive performs the Write command.
If read caching is enabled (RCD=0), then data written to the medium is retained in the cache to be made avail­able for future read cache hits. The same buffer space and segmentation is used as set up for read functions. The buffer segmentation scheme is set up or changed independently, having nothing to do with the state of RCD. When a write command is issued, if RCD=0, the cache is first checked to see if any logical blocks that are 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 the number of write data logical blocks exceed 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 medium.
If write caching is enabled (WCE=1), then the drive may return Good status on a write command after the data has been transferred into the cache, but before the data has been written to the medium. If an error occurs while writing the data to the medium, and Good status has already been returned, a deferred error will be gen erated.
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.
Ta bl e 18 shows the mode default settings for the drive.
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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 are 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.
To enable Prefetch, use 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 segments, 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).
When 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.

4.5.3 Optimizing cache performance for desktop and server applications

Desktop and server applications require different drive caching operations for optimal performance. This means it is difficult to provide a single configuration that meets both of these needs. In a desktop environment, you want to configure the cache to respond quickly to repetitive accesses of multiple small segments of data without taking the time to “look ahead” to the next contiguous segments of data. In a server environment, you
14 Cheetah 15K.4 FC Product Manual, Rev. B
want to configure the cache to provide large volumes of sequential data in a non-repetitive manner. In this case, the ability of the cache to “look ahead” to the next contiguous segments of sequential data is a good thing.
The Performance Mode (PM) bit controls the way the drive switches the cache buffer into different modes of segmentation. In “server mode” (PM bit = 0), the drive can dynamically change the number of cache buffer segments as needed to optimize the performance, based on the command stream from the host. In “desktop mode” (PM bit = 1), the number of segments is maintained at the value defined in Mode Page 8, Byte 13, at all times. For additional information about the PM bit, refer to the Unit Attention Parameters page (00h) of the Mode Sense command (1Ah) in the Fibre Channel Interface Product Manual, part number 77767496.
Cheetah 15K.4 FC Product Manual, Rev. B 15
16 Cheetah 15K.4 FC Product Manual, Rev. B

5.0 Reliability specifications

The following reliability specifications assume correct host and drive operational interface, including all inter­face timings, power supply voltages, environmental requirements and drive mounting constraints.
Seek error rate:
Read Error Rates
Recovered Data
Unrecovered Data
Miscorrected Data
Interface error rate:
MTBF: 1,400,000 hours Preventive maintenance: None required
1. Error rate specified with automatic retries and data correction with ECC enabled and all flaws reallocated.
1
Less than 10 errors in 108 seeks
Less than 10 errors in 1012 bits transferred (OEM default settings)
Less than 1 sector in 1015 bits transferred
Less than 1 sector in 1021 bits transferred
Less than 1 error in 1012 bits transferred with minimum receive eye. Less than 1 error in 1014 bits transferred with typical receive eye. See Section 9.6.4, "FC Differential input." on page 72

5.1 Error rates

The error rates stated in this manual assume the following:
• The drive is operated in accordance with this manual using DC power as defined in paragraph 6.2, "DC
power requirements."
• Errors caused by host system failures are excluded from error rate computations.
• Assume random data.
• Default OEM error recovery settings are applied. This includes AWRE, ARRE, full read retries, full write
retries and full retry time.

5.1.1 Recoverable Errors

Recovereable errors are those detected and corrected by the drive, and do not require user intervention.
Recoverable Data errors will use correction, although ECC on-the-fly is not considered for purposes of recov­ered error specifications.
Recovered Data error rate is determined using read bits transferred for recoverable errors occurring during a read, and using write bits transferred for recoverable errors occurring during a write.

5.1.2 Unrecoverable Errors

Unrecoverable Data Errors (Sense Key = 03h) are specified at less than 1 sector in error per 1015 bits trans­ferred. Unrecoverable Data Errors resulting from the same cause are treated as 1 error for that block.
Cheetah 15K.4 FC Product Manual, Rev. B 17

5.1.3 Seek errors

A seek error is defined as a failure of the drive to position the heads to the addressed track. After detecting an initial seek error, the drive automatically performs an error recovery process. If the error recovery process fails, a seek positioning error (Error code = 15h or 02h) will be reported with a Hardware error (04h) in the Sense Key. Recoverable seek errors are specified at Less than 10 errors in 10
8
seeks. Unrecoverable seek errors
(Sense Key = 04h) are classified as drive failures.

5.1.4 Interface errors

An interface error is defined as a failure of the receiver on a port to recover the data as transmitted by the device port connected to the receiver. The error may be detected as a running disparity error, illegal code, loss of word sync, or CRC error. The total error rate for a loop of devices is the sum of the individual device error rates.

5.2 Reliability and service

You can enhance the reliability of Cheetah K15.4 disc drives by ensuring that the drive receives adequate cool­ing. Section 6.0 provides temperature measurements and other information that may be used to enhance the service life of the drive. Section 8.3 provides recommended air-flow information.

5.2.1 Mean time between failure (MTBF)

The production disc drive achieves an MTBF of 1,400,000 hours when operated in an environment that ensures the case temperatures specified in Section specification limits of the operating environment will not affect MTBF performance. Operating the drive at case temperatures above these values will adversely affect the drive’s ability to meet specifications (see "Environmental limits").
6.4.1 are not exceeded. Short-term excursions up to the
Section 6.4,
The MTBF target is specified as device power-on hours (POH) for all drives in service per failure.
The following expression defines MTBF:
MTBF per measurement period = Estimated power-on operating hours in the period
Number of drive failures in the period
Estimated power-on operating hours means power-on hours per disc drive times the total number of disc drives in service. Each disc drive must have accumulated at least nine months of operation. Data is calculated on a rolling average base for a minimum period of six months.
MTBF is based on the following assumptions:
• 8,760 power-on hours per year
• 250 average on/off cycles per year
• Operating at nominal voltages
• System provides adequate cooling to ensure the case temperatures specified in Section 6.4.1 are not exceeded.
Drive failure means any stoppage or failure to meet defined specifications caused by drive malfunction.
A S.M.A.R.T. predictive failure indicates that the drive is deteriorating to an imminent failure and is considered an MTBF hit.

5.2.2 Preventive maintenance

No routine scheduled preventive maintenance is required.
18 Cheetah 15K.4 FC Product Manual, Rev. B
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