Fujitsu MAN3367FC - Enterprise 36.7 GB Hard Drive Product/Maintenance Manual page 55

(3) Automatic alternate block allocation
Automatic alternate block allocation at read operation
If the ARRE flag in the MODE SELECT parameter permits the automatic alternate block allocation,
the IDD automatically executes the alternate block allocation and data duplication on the defective
data block detected during the READ or READ EXTENDED command. This allocation method is
the same as with the REASSIGN BLOCKS command (alternate sector treatment).
Automatic alternate block allocation at write operation
If the AWRE flag in the MODE SELECT parameter permits the automatic alternate block allocation,
the IDD executes reassign processing to all the existing sectors in the servo frame where offtrack
error occurred during WRITE or WRITE EXTENDED or WRITE AND VERIFY command
processing and in the next servo frame.
EXTENDED command processing is successively executed for the following sectors.
Automatic alternate block allocation is made only once during the
execution of one command. If second defective block is detected, the
alternate block assignment processing for the first defective block is
executed but the alternate block assignment processing for the second
one is not executed and the command being executed terminates.
However, the initiator can recover the twice error by issuing the same
command again.
When an error is detected in a data block in the data area, recovery
data is rewritten and verified in automatic alternate block allocation
during the execution of the READ or READ EXTENDED command.
Alternate block allocation will not be made for the data block if
recovery is successful.
Example: Even if the data error which is recoverable by the WRITE
C141-E133-02EN
After completing reassignment, WRITE or WRITE
IMPORTANT
LONG command is simulated, automatic alternate block
allocation will not be made for the data block.
3.3 Defect Management
3-15