Disk Drive Operation
WA31273A / WA32543A / WA33203A / WA32163A / WA31083A / WA32162A5-17
The defect list contains two different tables, the first is data defective sectors and servo defective
sectors. The second is S-list, S-list is created to speed up the search for the R-list, it is used as the look
up table for the R-list.
5-5-4
Write Auto Reassign
The automatic defect allocation feature automatically maps out defective sectors identified during
execution of a write command. If drive gets write error during accessing data sector and error
recovery sequence can not recover the error, data sectors which are in that servo frame reassigned.
Features:
•
Support up to 50 sectors (expandable up to 114 sectors)
•
Use binary search method to minimize overhead
•
Capability to reassign not only write errors, but also read errors available.
•
Use more scratch pad to save variables during auto reassignment to minimize use of internal
memory.
Basic Operation:
•
Use all unused spare sectors of each zone for reassign
•
Reserve ½ track of each spare cylinder for auto reassign
•
Reassign List Table is initialized at the end of defect free process in factory test process
•
Reassign List Table Location
•
Disk: Cyl-0, Head-2,3, Sector-50-51
•
Buffer: 0x2A00 ~ 0x2BFF (0x2DFF)
•
Scanning the Defect List includes scanning the Reassign List includes scanning the Reassign List
during normal read/write operation.
•
Auto Reassign is done only by updating the Reassign List
5-5-5 Multi-burst ECC Correction
The drive uses a 144 bit Reed-Solomon code to perform error detection and correction. For each 512
byte block, the software error correction polynomial is capable of correcting:
•
one single burst error
•
three burst error
