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16 Constellation.2 SAS Product Manual, Rev. H
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.
6.1.4 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.
6.2 Reliability and service
You can enhance the reliability of Constellation.2 disk drives by ensuring that the drive receives adequate cool-
ing. Section 7.0 provides temperature measurements and other information that may be used to enhance the
service life of the drive. Section 11.2 provides recommended air-flow information.
6.2.1 Annualized Failure Rate (AFR) and Mean Time Between Failure (MTBF)
The production disk drive 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 7.5. Oper-
ation at case temperatures outside the specifications in Section 7.5 may increase the product AFR (decrease
the MTBF). The AFR (MTBF) is a population statistic not relevant to individual units.
The AFR (MTBF) specification is based on the following assumptions for Enterprise Storage System environ-
ments:
• 8760 power-on hours per year.
• 250 average on/off cycles per year.
• Operations at nominal voltages.
• Systems will provide adequate cooling to ensure the case temperatures specified in Section 7.5 are not
exceeded. Temperatures outside the specifications in Section 7.5 will increase the product AFR and
decrease the MTBF.
6.2.2 Preventive maintenance
No routine scheduled preventive maintenance is required.
6.2.3 Hot plugging the drive
When a disk is powered on by switching the power or hot plugged, the drive runs a self test before attempting
to communicate on its’ interfaces. When the self test completes successfully, the drive initiates a Link Reset
starting with OOB. An attached device should respond to the link reset. If the link reset attempt fails, or any
time the drive looses sync, the drive initiated link reset. The drive will initiate link reset once per second but
alternates between port A and B. Therefore each port will attempt a link reset once per 2 seconds assuming
both ports are out of sync.
If the self-test fails, the drive does not respond to link reset on the failing port.
Note. It is the responsibility of the systems integrator to assure that no temperature, energy, voltage haz-
ard, or ESD potential hazard is presented during the hot connect/disconnect operation. Discharge
the static electricity from the drive carrier prior to inserting it into the system.