Reassign Function; Auto Reassign Function - IBM IC25N020ATDA04 - Travelstar 20 GB Hard Drive Specifications

11.14 Reassign Function

The Reassign Function is used with read commands and write commands. The sectors of data for
reassignment are prepared as the spare data sector. The one entry can register 256 consecutive sectors
maximum.
This reassignment information is registered internally, and the information is available right after
completing the reassign function. Also the information is used on the next power on reset or hard reset.
If the number of the spare sector reaches 0 sector, the reassign function will be disabled automatically.
The spare sectors for reassignment are located in a reserved area. As a result of reassignment, the
physical location of logically sequenced sectors is dispersed.

11.14.1 Auto Reassign Function

The sectors that show some errors may be reallocated automatically when specific conditions are met.
The spare sectors for reallocation are located in a reserved area. The conditions for auto-reallocation are
described below.
Nonrecovered write errors
When a write operation can not be completed after the Error Recovery Procedure (ERP) is fully carried
out, the sector(s) are reallocated to the spare location. An error is reported to the host system only when
the write cache is disabled and the auto reallocation fails.
If the number of available spare sectors reaches 16 sectors, the write cache function will be disabled
automatically.
If the command is without retry and the write cache function is disabled, the auto reassign function is not
invoked.
Nonrecovered read errors
When a read operation fails after a defined ERP is fully carried out, a hard error is reported to the host
system. This location is registered internally as a candidate for the reallocation. When a registered
location is specified as a target of a write operation, a sequence of media verifications is performed auto-
matically. When the result of this verification meets the criteria, this sector is reallocated.
Recovered read errors
When a read operation for a sector failed once and then recovered at the specific ERP step, this sector of
data is reallocated automatically. A media verification sequence may be run prior to the relocation
according to the predefined conditions.
Travelstar 48GH, 30GN & 15GN hard disk drive specifications
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