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3.3
Write Cache
The IDD is equipped with a write cache function in order to reduce the INIT's command
processing time. If that operation is permitted by the MODE SELECT command (caching
parameters: Page code = 8, WCE bit), at the point when the IDD completes the transfer of all
data specified in the WRITE or WRITE EXTENDED command, it reports the GOOD status
and terminates the command.
If the write cache function is permitted, data transferred form the
INIT by a WRITE or WRITE EXTENDED command are written to
the disk media after the GOOD status is reported, so when an
unrecoverable write error is detected in that write operation,
sense data is generated. When those sense data is being held, the
IDD ordinarily responds to the command that is executed next by
a "CHECK" status (deferred error), notifying the INIT that sense
data is being held. However, ordinarily, it is troublesome for the
INIT to retry when there is an unrecoverable error in a write
cache operation, so adequate caution should be exercised when
using this function.
IMPORTANT
C141-E054-02EN
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