Error Rate; Media Defects; Load/Unload Function - Fujitsu MHZ2080BJ Product/Maintenance Manual

Device Overview

1.8 Error Rate

Known defects, for which alternative blocks can be assigned, are not included in
the error rate count below. It is assumed that the data blocks to be accessed are
evenly distributed on the disk media.
(1) Unrecoverable read error
Read errors that cannot be recovered by maximum read retries of drive without
user's retry and ECC corrections shall occur no more than 1 time when reading
data of 10
recovery procedure, and include read retries accompanying head offset operations.
(2) Positioning error
Positioning (seek) errors that can be recovered by one retry shall occur no more
than 1 time in 10

1.9 Media Defects

Defective sectors are replaced with alternates when the disk drive is formatted
prior to shipment from the factory (low level format). Thus, the hosts see a defect-
free device.
Alternate sectors are automatically accessed by the disk drive. The user need not
be concerned with access to alternate sectors.

1.10 Load/Unload Function

The Load/Unload function is a mechanism that loads the head on the disk and
unloads the head from the disk.
The product supports a minimum of 600,000 Load/Unload cycles.
Unload is a normal head unloading operation and the commands listed below are
executed.
• STANDBY command issued
•
STANDBY IMMEDIATE command issued
•
SLEEP command issued
• IDLE IMMEDIATE command (with unload feature) issued
•
Power Mode shifted with APM or APS feature.
Emergency Unload other than Unload is performed when the power is shut down
while the heads are still loaded on the disk.
The product supports the Emergency Unload a minimum of 20,000 times.
1-14
14
bits. Read retries are executed according to the disk drive's error
7
seek operations.
C141-E280