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Sense Data Error Recovery Methods
5 - 24 C141-E167
Remark:
1. When this function is specified (ARRE = "1"), the EER flag's specification in the MODE
SELECT parameter is made invalid and Read retry processing is performed up to the
number of times specified in the "Number of Retries during Read" parameter. If "0" is
specified in the DCR flag, correction processing of the data is performed afterward (see
Section 5.3.1 (3)). When "1" is specified in the DCR flag, ECC correction processing is
prohibited, so even if "1" is specified in the ARRE flag, auto alternate block allocation
processing will not be executed for errors in the data area.
2. When errors in the data area are recovered from by ECC correction processing, before
implementing alternate block allocation processing, rewriting of the recovered data and a
verify check (rereading) are performed. If data are recovered by rewriting, alternate block
allocation of that data block is not performed.
3. When a write operation is prohibited through the setting terminal, the auto alternate block
allocation processing specification is disabled.
(2) Auto alternate block allocation processing during a write operation 1
This function is enabled by specifying "1" in the AWRE flag in the MODE SELECT parameters.
Furthermore, this function is applicable to the following commands only.
• WRITE command
• WRITE EXTENDED command
• WRITE AND VERIFY
When this function is permitted, if, during read processing to the data area, up to 8 unrecoverable
read errors will be logged by the drive. The log will be checked before every WRITE command.
If a WRITE command has the same LBA in the log, then Sector Size +2 bytes of data will be written
to the sector, and it will be verified with less powered ECC. If the verify is successful, then the
AWRE will not be performed. (no sense will be reported).
If the verify is unsuccessful, then check the spare. Write the data onto the new spare, and verify it. If
the verify is successful, then the reallocation will be proceeded. If the verify is unsuccessful, then the
drive will add the defective spare onto the G-List, and then choose another spare, and try the same
thing to the new spare until the verify completes successfully. After reallocates all of the logged
LBA included in a WRITE command the drive will start the write operation.
(3) Auto alternate block allocation processing during a write operation 2
This function is enabled by specifying "1" in the AWRE flag in the MODE SELECT parameters.
Furthermore, this function is applicable to the following commands only.
• WRITE command
• WRITE EXTENDED command
When this function is permitted, if, during WRITE/WRITE EXTENDED command detects any
Servo error (e.g. Write offtrack error) and cannot be recovered within pre-determined retry number
(specified in Mode Parameter). For the sectors around defective Servo, alternate blocks are allocated
and the data of this WRITE commands are re-written.