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4.3.2
Auto Alternate Block Allocation Processing
The IDD is equipped with a function which automatically executes alternate block allocation
processing for defective data blocks detected during execution of the WRITE, WRITE
EXTENDED, WRITE AND VERIFY, READ and READ EXTENDED commands.
(1)
Auto Alternate Block Allocation Processing during a Write Operation
This function is enabled by specifying "1" in the AWRE flag of the MODE SELECT
parameters. Furthermore, this function is applicable to the following commands only.
• WRITE Command
• WRITE EXTENDED Command
• WRITE AND VERIFY Command (Write operation)
When this function is permitted, if, during write processing to the data area, an error which is an
object of retry processing is detected, and which it is impossible to recover from even when reading
is retried (see item 4.3.1 (2)) the number of times specified in the "Number of Retries during Write"
field in the MODE SELECT parameters, the IDD allocates an alternate block for that data block and
executes write processing to the data area of the alternate block. Alternate block allocation
processing is the same as processing with the REASSIGN BLOCKS command.
This function is applied once only during execution of one command.
allocation processing and write processing are executed for the first defective data block to be
detected during execution of a command, but if a second defective data block is detected, the
command that is being executed at that point is terminated with an error. However, by the
INIT's reissuing the same command, auto alternate block allocation is applied sequentially and
error recovery can be attempted.
(2)
Auto Alternate Block Allocation Processing During a Read Operation
This function is enabled by specifying "1" in the ARRE flag in the MODE SELECT
parameters. Furthermore, this function is applicable to the following commands only.
• READ Command
• READ EXTENDED Command
When this function is permitted, if, during read processing to the data area, an error which is
an object of retry processing is detected, and which it is impossible to recover from even when
reading is retried (see item 4.3.1 (2)) the number of times specified in the "Number of Retries
during Read" field in the MODE SELECT parameters, the IDD allocates an alternate block for
that data block and executes copying of the alternate block to the data area. Alternate block
allocation processing is the same as processing with the REASSIGN BLOCKS command.
Furthermore, recovered data copied to the alternate block are data which are read out, skipping
the ID area, if there is an ID area, or they are data which have been corrected through the ECC.
This function is applied once only during execution of one command. Alternate block
allocation processing and copying are executed for the first defective data block to be detected
during execution of a command, but if a second defective data block is detected, the command
that is being executed at that point is terminated with an error. However, by the INIT's
reissuing the same command, auto alternate block allocation is applied sequentially and error
recovery can be attempted.
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C141-E039-01EN
Alternate block
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