Fujitsu MAE3091LC SERIES, Product Manual

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C141-E064-03EN 3 - 16
(3) Automatic alternate block allocation
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 EXTENDED command. This
allocation method is the same as with the REASSIGN BLOCKS command (alternate sector
treatment).
IMPORTANT
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 LONG command is simulated, automatic
alternate block allocation will not be made for the data
block.