Auto Reassign Function - Hitachi HDS723020BLA642 Specifications

9.9 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.
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 sectors, the reassign function will be disabled automatically.
The spare tracks for reassignment are located at regular intervals from Cylinder 0. As a result of reassignment,
the physical location of logically sequenced sectors will be dispersed.
9.9.1

Auto Reassign Function

The sectors those show some errors may be reallocated automatically when specific conditions are met. The
spare tracks for reallocation are located at regular intervals from Cylinder 0. The conditions for auto-reallocation
are described below.
Non recovered 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 is failed.
If the write cache function is ENABLED, and when the number of available spare sectors reaches 0 sectors,
both auto reassign function and write cache function are disabled automatically.
Non recovered read errors
When a read operation is failed after 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 verification is performed automatically. 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 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
pre-defined conditions.
Hitachi hard disk drive specifications
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