Hitachi HUS154530VLF400 User Manual

Hitachi Ultrastar 15K450 (FC-AL) Hard Disk Drive Specification

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The REASSIGN BLOCKS command requests the drive to reassign a logical block to an available spare. The REASSIGN 
BLOCKS command attempts to allocate spare blocks on a spare track. The LBA is transferred to the drive during the DATA 
OUT phase. One to four blocks may be specified for relocation per REASSIGN BLOCKS command.

Reassignment is complete upon the completion of the REASSIGN BLOCKS command. At this time, the defective logical 
block address has been added to the Glist.

All data is preserved during a reassign command except for the target LBA data. The Mode Page 0h DRRT (Disable Restore 
Reassign Target) bit determines if the reassign blocks command will attempt to recover the Target LBA data. If the Target can-
not recover the data at the Target LBA then the Initiator will have to restore the data after the REASSIGN BLOCKS command 
completes successfully. 

If the reassignment begins to move data and is interrupted or fails to complete successfully, the Target enters a degraded mode 
of operation. In this mode data can be read but writing to the drive is prohibited.

Upon successful completion of this command, the location of the physical sectors reassigned during the command are added to 
the Glist. The reassigned sectors are marked defective and cannot be accessed again until after a format operation discards the 
Glist.