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(1)
Recovery Processing for Errors on the SCSI Bus
The IDD does not perform recovery processing for error detected on the SCSI bus. When
error recovery is impossible, or when a major error related to SCSI bus protocols is detected,
the IDD may transfer the SCSI bus forcibly to the BUS FREE phase and clear the command
that is currently being executed.
Table 1.4
Item
1
MESSAGE OUT phase parity error
2
COMMAND phase parity error
3
DATA OUT phase parity error
4
Received INITIATOR DETECTED ERROR message. "Check Condition" Status
5
Received MESSAGE PARITY ERROR message.
6
RESELECTION phase time-out
(2)
Recovery Procedures for Disk Drive Errors
The IDD executes error recovery listed in Table 1.5 for an error detected during access to data
on the disk. Note that the recovery increases command processing time because of rotation
delay for repositioning to the data block on the disk or initialization of the positioning control
system.
The INIT can use the MODE SELECT parameter Page 1 (read/write error recovery parameter),
Page 7 (verify error recovery parameter), and Page 21 (additional error recovery parameter) to
control the retry count. However, use the default value specified by the IDD in general
operation.
Table 1.5
Item
Type of Error
1
Seek Error
2
Uncorrectable Data Error
3
Correctable Data Error
Note
The execution start timing of this automatic readjustment operation generally cannot be
predicted by the INIT. The automatic readjustment operation is performed there are no
commands being executed or in the queue, but execution of commands issued
immediately after the IDD starts the readjustment operation, are forced to wait until the
readjustment operation is completed.
Outline of SCSI Bus Error Recovery Processing
Type of Error
Outline of Disk Drive Error Recovery Processing
Rezero (Return to Zero Cylinder), with positioning control
system readjustment repositioning in the data block.
Reread
Correct according to ECC.
C141-E039-01EN
Error Recovery Processing
"Check Condition" Status
"Check Condition" Status
"Check Condition" Status
"Check Condition" Status
Re-execute RESELECTION phase.
Error Recovery Processing
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