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Constellation.2 SAS Product Manual, Rev. H 15
6.0 Reliability specifications
The following reliability specifications assume correct host and drive operational interface, including all inter-
face timings, power supply voltages, environmental requirements and drive mounting constraints.
6.1 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 7.3, "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.
6.1.1 Recoverable Errors
Recoverable 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 recov-
ered 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.
6.1.2 Unrecoverable Errors
An unrecoverable data error is defined as a failure of the drive to recover data from the media. These errors
occur due to head/media or write problems. Unrecoverable data errors are only detected during read opera-
tions, but not caused by the read. If an unrecoverable data error is detected, a MEDIUM ERROR (03h) in the
Sense Key will be reported. Multiple unrecoverable data errors resulting from the same cause are treated as 1
error.
Seek error rate: Less than 10 errors in 10
8
seeks
Read Error Rates
1
1. Error rate specified with automatic retries and data correction with ECC enabled and all flaws reallocated.
Recovered Data Less than 10 errors in 10
12
bits transferred (OEM default settings)
Unrecovered Data Less than 1 sector in 10
15
bits transferred
Miscorrected Data Less than 1 sector in 10
21
bits transferred
Interface error rate: Less than 1 error in 10
12
bits transferred
Mean Time Between Failure (MTBF): 1,400,000 hours
Annualized Failure Rate (AFR): 0.62%
Preventive maintenance: None required