Western Digital scorpio black MX375M, Техническое справочное руководство

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WD Scorpio MX375M Product Features
2679-771293-A01 RELEASED 11/17/10 (WD CONFIDENTIAL) 19
3.6.9 Automatic Defect Retirement
The automatic defect retirement feature automatically maps out defective sectors while reading or
writing. If a defective sector appears, the drive finds a spare sector.
The following item is specific to automatic defect retirement on writes (write auto-relocation):
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Data is always written to disk (using automatic defect retirement if required) and no error is
reported.
The following item is specific to automatic defect retirement on reads (read auto-relocation):
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When host retries are enabled, the drive will internally flag any unrecoverable errors (DAMNF or
ECC). This flagging allows subsequent write commands to this location to relocate the sector only
if the sector test fails.
3.6.10 Error Recovery Process
The drive has five means of error recovery:
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ECC On-the-Fly
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Read/Write Retry Procedure
„
Extended Read Retry Procedure
ECC On-the-Fly – If an ECC error occurs, the drive attempts to correct it on-the-fly without retries.
Data can be corrected in this manner without performance penalty. The details of the correction
algorithm appear in the next section.
Read/Write Retry Procedure – This retry procedure is used by all disk controller error types. If the
procedure succeeds in reading or writing the sector being tried, then recovery is complete and the
controller continues with the command. Each retry operation also checks for servo errors. The
procedure ends when error recovery is achieved or when all possible retries have been attempted.
Extended Read Retry Procedure – This retry procedure tries combinations of positive/negative track
offsets and data DAC manipulations to recover the data. This retry procedure applies only to read data
recovery. The Read/Write Retry procedure performs the actual retry operation.
When an extended retry operation is successful, the controller continues with the command. The
controller clears any changes in track offset or data DAC settings before the command continues.