Fujitsu MAN3735 Manuale Utente

C141-E124-01EN

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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.

Item

Type of Error

Error Recovery Processing

1

Seek Error

Rezero (Return to Zero Cylinder), readjustment of positioning
control system, and repositioning to the data block.

2

Uncorrectable Data Error

Reread

3

Correctable Data Error

Correct by ECC.

The execution start timing of this automatic readjustment operation generally cannot be
predicted by the INIT.  The automatic readjustment operation is performed when 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.