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5.0
Reliability specifications
The following reliability specifications assume correct host and drive operational interface, including all interface timings, power supply voltages,
environmental requirements and drive mounting constraints.
Seek error rate:
1
Read Error Rates
Recovered Data
Unrecovered Data
Miscorrected Data
Interface error rate:
Mean Time Between Failure (MTBF):
Annualized Failure Rate (AFR):
Preventive maintenance:
1.
Error rate specified with automatic retries and data correction with ECC enabled and all flaws reallocated.
5.1
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
• 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.
5.1.1
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 recovered 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.
5.1.2
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 operations, 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.
5.1.3
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
seek errors (Sense Key = 04h) are classified as drive failures.
5.1.4
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.
Seagate Exos 2X14 SAS Product Manual, Rev. A
8
Less than 10 errors in 10
seeks
12
Less than 10 errors in 10
bits transferred (OEM default settings)
15
Less than 1 sector in 10
bits transferred
21
Less than 1 sector in 10
bits transferred
12
Less than 1 error in 10
bits transferred
2,500,000 hours
0.35%
None required
Section 6.4, DC power requirements
Reliability specifications
8
seeks. Unrecoverable
15
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