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CHEETAH 15K.7 SAS PRODUCT MANUAL, REV. F 12
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.
5.1 ERROR RATES
The error rates stated in this manual assume the following:
• The drive is operated per this specification using DC power as defined in this manual (see Section 6.2).
• 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.
• Error rate specified with automatic retries and data correction with ECC enabled and all flaws reallocated
5.1.1 Recoverable Errors
Recoverable errors are those detected and corrected by the drive, and do not require user intervention.
Recoverable Data errors use retries and correction. Application of ECC on-the-fly correction alone is not considered a
Recovered Data error.
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
Unrecoverable Data Errors (Sense Key = 03h) are specified at less than 1 sector in error per 10
16
bits transferred.
Unrecoverable Data Errors resulting from the same cause are treated as 1 error for that block.
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
8
seeks. Unrecoverable 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.
5.2 RELIABILITY AND SERVICE
You can enhance the reliability of Cheetah disk 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
10.2 provides recommended air-flow information.
Seek error rate: Less than 10 errors in 10
8
seeks
Read Error Rates
Recovered Data Less than 10 errors in 10
12
bits transferred (OEM default settings)
Unrecovered Data Less than 1 sector in 10
16
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
MTBF 1,600,000 hours
AFR 0.55%
Preventive maintenance: None required