Fujitsu MBC2036RC, MBC2073RC, MBA3300RC, MBA3147RC, MBA3073RC specifications Defect Management

7.1 Defect Management

c.Alternate block allocation processing

Alternate block allocation processing is implemented by the FORMAT UNIT command, REASSIGN BLOCKS command or "Auto Alternate Block Allocation Processing." In sector slip processing, the defective sectors re excluded and logical data blocks are located in physically consecutive sectors, but when alternate block processing is performed, the affected logical data blocks are located in spare sectors which are not physically consecutive with the previous and following logical data blocks which are physically located on the disk.

−Alternate block allocation processing during FORMAT UNIT command execution

With the FORMAT UNIT command, alternate block allocation is done by sector slip processing until all the spare sectors within the same cell have been used up for defective sectors included in the type of defect list (P, G or D) specified in the command. When all the spare sectors in the same cell have been used up, subsequent defective sectors in that cell are treated by allocating spare sectors in an alternate cell by alternate sector processing.

After implementing this alternate block allocation and initializing the disk media, at times when a data block Verify (Certification) operation is not prohibited, the HDD, reads all the initialized data blocks and verifies their normalcy. If a defective data block is detected during this processing, the HDD generates the C List as defect position information and allocates alternate blocks by alternate sector processing for those defective data blocks. In this case, alternate blocks are allocated in spare sectors in an alternate cell.

−Alternate block allocation processing by the REASSIGN BLOCKS command

With the REASSIGN BLOCKS command, alternate block allocation is performed by alternate sector processing for defective logical data blocks specified by the INIT. In this case, alternate blocks are allocated in spare sectors in an alternate cell.

−Auto alternate block allocation processing

If auto alternate block allocation processing is permitted by the AWRE flag or the ARRE flag of the MODE SELECT parameters, the HDD executes alternate clock allocation automatically by alternate sector processing for defective data blocks detected during execution of the WRITE, WRITE EXTENDED, WRITE AND VERIFY, READ and READ EXTENDED commands. The alternate block allocation method in this case is the same as in the case of the REASSIGN BLOCKS command. See the description in Section 6.3.2 concerning "Auto Alternate Block Allocation Processing".

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