IBM Deskstar 120 GXP, Specifications

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9.11 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.
!
The retry bit of Write Sectors is ignored when write cache is enabled.
9.12 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 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 automatically disabled.
The spare sectors for reassignment are located in the reserved area. As a result of reassignment the
physical location of logically sequenced sectors will be dispersed.
9.13 Auto Reassign function
The sectors which show some errors may be reallocated automatically when specific conditions are met.
The spare sectors for reallocation are located at the end of drive. The conditions for auto-reallocation are
described below.
9.13.1 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.
9.13.2 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.
Deskstar 120GXP hard disk drive specifications
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