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14
5.1.4
Seek errors
A seek error is defined as a failure of the drive to position the heads to the addressed track. There shall be no
more than ten recoverable seek errors in 10
drive automatically performs an error recovery process. If the error recovery process fails, a seek positioning
error (15h) is reported with a Medium error (3h) or Hardware error (4h) reported in the Sense Key. This is an
unrecoverable seek error. Unrecoverable seek errors are classified as failures for MTBF calculations. Refer to
to the SCSI Interface Product Manual, part number 75789509, for Request Sense information.
5.2
Reliability and service
You can enhance the reliability of Barracuda 18XL 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 8.3.1 provides recommended air-flow information.
5.2.1
Mean time between failure
The production disc drive shall achieve an MTBF of 1,200,000 hours when operated in an environment that
ensures the case temperatures specified in Section 6.4.1, Table 3, Column 2 are not exceeded. Short-term
excursions up to the specification limits of the operating environment will not affect MTBF performance. Contin-
ual or sustained operation at case temperatures above the values shown in Table 3, Column 2 may degrade
product reliability.
The following expression defines MTBF
MTBF per measurement period
Estimated power-on operation hours means power-up hours per disc drive times the total number of disc drives
in service. Each disc drive shall have accumulated at least nine months of operation. Data shall be calculated
on a rolling average base for a minimum period of six months.
Drive failure means any stoppage or substandard performance caused by drive malfunction.
5.2.2
Preventive maintenance
No routine scheduled preventive maintenance shall be required.
5.2.3
Service life
The drive shall have a useful service life of five years. Depot repair or replacement of major parts is permitted
during the lifetime (see Section 5.2.4).
5.2.4
Service philosophy
Special equipment is required to repair the drive HDA. In order to achieve the above service life, repairs must
be performed only at a properly equipped and staffed service and repair facility. Troubleshooting and repair of
PCBAs (Printed Circuit Board Assemblies) in the field is not recommended, because of the extensive diagnos-
tic equipment required for effective servicing. Also, there are no spare parts available for this drive. Drive war-
ranty 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 since there are no user purchasable parts in the drive.
8
physical seek operations. After detecting an initial seek error, the
Estimated power-on operating hours in the period
=
Number of drive failures in the period
Barracuda 18XL Product Manual, Rev. A
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