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Cheetah 10K.6 FC Product Manual, Rev. B 13
5.0 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
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 paragraph 6.2, "DC
power requirements."
• The drive has been formatted with the FC-AL Format command.
• Errors caused by media defects or host system failures are excluded from error rate computations.
• Assume random data.
5.1.0.1 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. The total error rate for a loop of devices is the sum of the individual device error
rates.
5.1.1 Environmental interference
When evaluating systems operation under conditions of electromagnetic interference (EMI), the performance
of the drive within the system is considered acceptable if the drive does not generate an unrecoverable condi-
tion.
An unrecoverable error, or condition, is defined as one that:
• is not detected and corrected by the drive itself
• is not detected from the error or fault status provided through the drive or FC-AL interface
• is not recovered by normal drive or system recovery procedures without operator intervention
5.1.2 Write errors
Write errors can occur as a result of media defects, environmental interference, or equipment malfunction.
Therefore, write errors are not predictable as a function of the number of bits passed.
If an unrecoverable write error occurs because of an equipment malfunction in the drive, the error is classified
as a failure affecting MTBF. Unrecoverable write errors are those that cannot be corrected within two attempts
at writing the record with a read verify after each attempt (excluding media defects).
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 (15h) is reported with a Medium error (3h) or Hardware error (4h) reported in the
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 with minimum receive eye
Less than 1 error in 10
14
bits transferred with typical receive eye
(see Section 9.6.4, "Differential PECL input." on page 61)
MTBF 1,200,000 hours
Service life 5 years
Preventive maintenance None required