Error Rate; Reliability - Fujitsu MAH3182MC Maintenance Manual

2.1.4

Error rate

Errors detected during initialization and replaced by alternate block assignments are not included
in the error rate. Data blocks to be accessed should be distributed over the disk medium equally.
(1) Unrecoverable error rate
Errors which cannot be recovered within 63 retries and ECC correction should not exceed 10 per
15
10 bits.
(2) Positioning error rate
Positioning errors which can be recovered by one retry should be 10 or less per 10
2.1.5

Reliability

(1) Mean Time Between Failures (MTBF)
MTBF of the IDD during its life time is 1,000,000 hours (operating: 24 hours/day, 7 days/week
average DE surface temperature: 40°C or less).
Note:
The MTBF is defined as:
MTBF=
Failure of the equipment means failure that requires repair, adjustments, or replacement.
Mishandling by the operator, failures due to bad environmental conditions, power trouble, host
system trouble, cable failures, or other failures not caused by the equipment are not considered.
(2) Mean Time To Repair (MTTR)
Data loss
For MAH and MAJ series, Reed Solomon codes are applied for their
ECC. The sector-data is divided into 4 interleaving sectors, and
ECC is performed in each sector where the maximum number of
errors (up to 5 byte) can be corrected. [Total maximum byte: 5 byte
x 4 ( interleave) = 20 byte]
If the error of read sector keeps allowable error byte number,
correction is performed. However, if error byte exceeds its
allowable number, correction may not be performed properly.
Operating time (hours) at all field sites
The number of equipment failures from all field sites
C141-E103-01EN
CAUTION
8
seeks.
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