Data Format
If above errors are detected during FORMAT UNIT command, the HDDs allocate the alternate block(s) to the defective data blocks. Reassign procedure itself is the same as one in REASSIGN BLOCKS command.
*1 Certification is permitted when DCRT flag is cleared (DCRT flag=0) in FORMAT UNIT command.
The HDDs check all initialized logical data blocks by reading them out after the above alternate block allocation is made to initialize (format) the disk.
(2)Alternate block allocation by REASSIGN BLOCKS command
When the REASSIGN BLOCKS command is specified, the alternate block is allocated to the defective logical data block specified by the initiator by means of alternate sector treatment. The alternate block is allocated to unused spare sectors in the alternate cylinder.
Figure 3.8 is examples of the alternate block allocation by the REASSIGN BLOCKS command.
Example Reassign: Block 16
: n represents a logical data block number
: Defective sector
: Unused spare sector
