Seagate ST3300655LC Cheetah 15K.5 SCSI Product Manual - Page 21

Seek errors, Annualized Failure Rate AFR and Mean Time Between Failures MTBF, Preventive maintenance

Get Seagate ST3300655LC PDF manuals and user guides View all Seagate ST3300655LC manuals
Add to My Manuals
Save this manual to your list of manuals

Page 21 highlights

6.1.3 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 108 seeks. Unrecoverable seek errors (Sense Key = 04h) are classified as drive failures. 6.2 Reliability and service You can enhance the reliability of Cheetah 15K.5 SCSI disc drives by ensuring that the drive receives adequate cooling. Section 7.0 provides temperature measurements and other information that may be used to enhance the service life of the drive. Section 9.3 provides recommended air-flow information. 6.2.1 Annualized Failure Rate (AFR) and Mean Time Between Failures (MTBF) These drives shall achieve an AFR of 0.62% (MTBF of 1,400,000 hours) when operated in an environment that ensures the HDA case temperatures do not exceed the values specified in Section 7.4.1. Operation at case temperatures outside the specifications in Section 7.4.1 may increase the AFR (decrease the MTBF). AFR and MTBF statistics are population statistics that are not relevant to individual units. AFR and MTBF specifications are based on the following assumptions for Enterprise Storage System environments: • 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 7.4.1 are not exceeded. 6.2.2 Preventive maintenance No routine scheduled preventive maintenance shall be required. Cheetah 15K.5 SCSI Product Manual, Rev. J 15

  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
  • 11
  • 12
  • 13
  • 14
  • 15
  • 16
  • 17
  • 18
  • 19
  • 20
  • 21
  • 22
  • 23
  • 24
  • 25
  • 26
  • 27
  • 28
  • 29
  • 30
  • 31
  • 32
  • 33
  • 34
  • 35
  • 36
  • 37
  • 38
  • 39
  • 40
  • 41
  • 42
  • 43
  • 44
  • 45
  • 46
  • 47
  • 48
  • 49
  • 50
  • 51
  • 52
  • 53
  • 54
  • 55
  • 56
  • 57
  • 58
  • 59
  • 60
  • 61
  • 62
  • 63
  • 64
  • 65
  • 66
  • 67
  • 68
  • 69
  • 70
  • 71
  • 72
  • 73
  • 74
  • 75
  • 76
  • 77
  • 78
  • 79
  • 80
  • 81
  • 82
  • 83
  • 84
  • 85
  • 86
  • 87
  • 88
Cheetah 15K.5 SCSI Product Manual, Rev. J
15
6.1.3
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.
6.2
Reliability and service
You can enhance the reliability of Cheetah 15K.5 SCSI disc drives by ensuring that the drive receives ade-
quate cooling. Section 7.0 provides temperature measurements and other information that may be used to
enhance the service life of the drive. Section 9.3 provides recommended air-flow information.
6.2.1
Annualized Failure Rate (AFR) and Mean Time Between Failures (MTBF)
These drives shall achieve an AFR of 0.62% (MTBF of 1,400,000 hours) when operated in an environment that
ensures the HDA case temperatures do not exceed the values specified in Section 7.4.1.
Operation at case temperatures outside the specifications in Section 7.4.1 may increase the AFR (decrease
the MTBF). AFR and MTBF statistics are population statistics that are not relevant to individual units.
AFR and MTBF specifications are based on the following assumptions for Enterprise Storage System environ-
ments:
•
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 7.4.1 are not
exceeded.
6.2.2
Preventive maintenance
No routine scheduled preventive maintenance shall be required.