Write Cache Function; Reassign Function; Auto Reassign Function - Hitachi ic35l060avv207-0 - Deskstar 60 GB Hard Drive Specifications

9.10 Write cache function

Write cache is a performance enhancement whereby the device reports the completion of the write com-
mand (Write Sectors, Write Multiple, and Write DMA) to the host as soon as the device has received all of
the data into its buffer. The device assumes the responsibility for subsequently writing the data onto the
disk.
While writing data after completed acknowledgment of a write command, soft reset or hard reset
does not affect its operation. However power off terminates the writing operation immediately and
unwritten data is lost.
The Soft reset, Standby (Immediate) command, and Flush Cache commands during the writing of the
cached data are executed after the completion of writing to media. So the host system can confirm
the completion of write cache operation by issuing a Soft reset, Standby (Immediate) command, or
Flush Cache command to the device. before power off.

9.11 Reassign function

The Reassign function is used with read commands and write commands. The sectors of data for re-
assignment are prepared as the spare data sector.
This reassignment information is registered internally and the information is available right after complet-
ing 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 automatically disabled.
The spare sectors 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.

9.11.1 Auto Reassign function

The sectors which 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.
9.11.1.1 Nonrecovered write errors
When a write operation cannot 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 has failed.
If the Write Cache function is ENABLED when the number of available spare sectors reaches 0 sector,
both Auto Reassign function and Write Cache function are automatically disabled.
9.11.1.2 Nonrecovered read errors
When a read operation has 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 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.
9.11.1.3 Recovered read errors
When a read operation for a sector has failed once and then has recovered at the specific ERP step, this
sector of data is automatically reallocated. A media verification sequence may be run prior to the
reallocation according to the predefined conditions.
Deskstar 180GXP hard disk drive specifications
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