Seagate Cheetah 73LP FC ST336605FC, Руководство по эксплуатации продукта

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14 Cheetah 73LP FC Product Manual, Rev. D
Sense Key. This is an unrecoverable seek error. Unrecoverable seek errors are classified as failures for MTBF
calculations. Refer to the
Fibre Channel Interface Manual , part number 77767496, for Request Sense informa-
tion.
5.2 Reliability and service
You can enhance the reliability of Cheetah 73LP FC disc drives by ensuring that the drive receives adequate
cooling. Section 6.0 provides recommended air-flow information, temperature measurements, and other infor-
mation, which you can use to enhance the service life of the drive.
5.2.1 Mean time between failure (MTBF)
The production disc drive achieves an MTBF of 1,200,000 hours when operated in an environment that
ensures the case temperatures specified in Section 6.4.1 are not exceeded. Short-term excursions up to the
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 Section 6.4,
"Environmental limits".
The MTBF target is specified as device power-on hours (POH) for all drives in service per failure.
The following expression defines MTBF:
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.
5.2.3 Service life
The drive has a useful service life of five years. Depot repair or replacement of major parts is permitted during
the lifetime.
5.2.4 Service philosophy
Special equipment is required to repair the drive HDA. To achieve the above service life, repairs must be per-
formed only at a properly equipped and staffed Seagate service and repair facility. Troubleshooting and repair
of PCBs in the field is not recommended because of the extensive diagnostic equipment required for effective
servicing. There are not spare parts available for this drive. The drive warranty is voided if the HDA is opened.
5.2.5 Service tools
No special tools are required for site installation or recommended for site maintenance. Refer to Section 5.2.4.
The depot repair philosophy of the drive precludes the necessity for special tools. Field repair of the drive is not
practical because users cannot purchase individual parts for the drive.
MTBF per measurement period = Estimated power-on operating hours in the period
Number of drive failures in the period