Alternate Block Allocation Processing - Fujitsu MAX3073NC - SCSI,80, Dell DC961,Hard Drive Scsi Logical Interface Specifications

(3) Reading and verification of data
Issue the READ, READ EXTENDED or VERIFY command and verify that the data written to the disk
media in item (2) were read correctly.
To verify reading of data, it is recommended that reading of the same data block be done at lease 2 times,
but the number of times verification is performed is determined by the conditions on the system. If
reading of all data is completed normally, it can be recognized that use of that data block can be used
normally.
(4) Error verification
When an error related to the disk media (Sense Key = 3: MEDIUM ERROR) occurs during writing of
the data pattern (see item (2)) or verification of data reading (see item (3)), reexecute the rewriting and
reading verification combination (two times) at least 8 times.
When the same type of error occurs even once during reexecution, it is recommended that the INIT treat
that data block as a defective block. If the reexecution of verification is completed normally every time,
it should be regarded that that data block can be used normally.
6.4

Alternate Block Allocation Processing

If errors on the disk media which cannot be recovered from are detected, or if a recoverable error occurs
repeatedly in the same data block, it is necessary for the INIT to allocate an alternate block for the data
block where the error occurred using the REASSIGN BLOCKS command. The procedure for alternate
block processing is shown below.
Note:
An attempt will be made to copy the contents of the data area of the logical data block specified in
the "Defect Data" list to the alternate block allocated by this command, but in some cases, the data
cannot be copied. Confirmation of the contents of data in the allocated alternate block, saving of
data before issuing this command and restoring of data after executing this command are the
responsibility of the INIT.
1) Verify data blocks in accordance with the procedure in Section 6.3 for data blocks where error occur.
When such a data block is judged to be normal, alternate block allocation need not be implemented.
In this case, rewrite the original data to that data block if necessary. When the data block is judged
to be defective, implement the processing in item 2) and after.
2) Specify a logical block address for a data block which is judged to be defective and issue the
REASSIGN BLOCKS command.
3) If the REASSIGN BLOCKS command is terminated normally, verify that logical data block
according to the procedure in Section 6.3. If that data block is judged to be correct, allocate an
alternate block and terminate processing. When the data block is judged to be defective, return to 2)
and issue the REASSIGN BLOCKS command again, then try reallocating another alternate block for
that logical data block.
C141-C010
6.4 Alternate Block Allocation Processing
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