IBM DTCA-24090 Hard Drive Specifications - Page 95

Reassign Function

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10.10 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 assured number of the spare sectors is a minimum of 1230 sectors. 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 at reserved area. As a result of reassignment, the physical location of logically sequenced sectors will be dispersed. 10.10.1 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 at reserved area. The conditions for auto-reallocation are described below. When a device shipped from IBM, a minimum of 1230 usable spare sectors are available. 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 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. Non recovered read errors When a read operation fails after defined E R P is fully carried out, a hard error is reported to the host system. This location is registerred internally as a candidate for the reallocation. When a registerred 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 E R P 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. General Operation Descriptions 87

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10.10
Reassign Function
The reassign Function is used with read commands and write commands.
The sectors of data for reassign-
ment are prepared as the spare data sector.
The assured number of the spare sectors is a minimum of 1230
sectors.
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 at reserved area. As a result of reassignment, the physical
location of logically sequenced sectors will be dispersed.
10.10.1
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 at reserved area.
The conditions for auto-reallocation are described
below.
When a device shipped from IBM, a minimum of 1230 usable spare sectors are available.
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 fails.
If the number of available spare sectors reaches 16 sectors, the write cache function will be disabled automat-
ically.
If the command is without retry and the write cache function is disabled, the auto reassign function is not
invoked.
Non recovered read errors
When a read operation fails after defined ERP is fully carried out, a hard error is reported to the host system.
This location is registerred internally as a candidate for the reallocation. When a registerred location is speci-
fied 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.
General Operation Descriptions
87