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US 8,094,396 B1Granted
Media defect scan
AssigneeWestern Digital Technologies, Inc.
InventorsBaoliang Zhang, Teik Ee Yeo, Johanes S. Ma
Life of this patent
Estimating the term…
Abstract
A disk drive is disclosed comprising a disk, a head for writing data to the disk, and control circuitry coupled to the head. The control circuitry is operable to write data to the plurality of data tracks, read a first data area of a first data track to generate a first read back signal, determine a first quality metric and a channel flag in response to the first read back signal, determine that the first quality metric exceeds a first threshold, apply additional stress to the first data area, reread the first data area to generate a second read back signal, determine a second quality metric in response to the second read back signal, and determine whether the second quality metric exceeds a second threshold.
Claims31
A disk drive comprising:
- a disk comprising a plurality of data tracks;
- a head actuated over the disk;
- and
- control circuitry coupled with the head operable to:
- write data to the plurality of data tracks;
- read a first data area of a first data track to generate a first read back signal;
- determine a first quality metric and a channel flag in response to the first read back signal;
- determine that the first quality metric exceeds a first threshold and is below a third threshold;
- apply additional stress to the first data area;
- reread the first data area to generate a second read back signal;
- determine a second quality metric in response to the second read back signal;
- and
- determine whether the second quality metric exceeds a second threshold.
10 more elements
A disk drive comprising:
- a disk comprising a plurality of data tracks;
- a head actuated over the disk;
- and
- control circuitry coupled with the head operable to:
- write data to the plurality of data tracks;
- read a first data area of a first data track to generate a first read back signal;
- determine a first quality metric and a channel flag in response to the first read back signal;
- determine that the first quality metric exceeds a first threshold;
- apply additional stress to the first data area;
- reread the first data area to generate a second read back signal;
- determine a second quality metric in response to the second read back signal;
- and
- determine whether the second quality metric exceeds a second threshold,
- wherein the first and second quality metric comprise percentage amplitude drop-outs of the read back signal, and wherein the percentage amplitude drop-outs of the read back signal comprises an average value of an amplitude drop-out averaged over a sample period P of the read back signal.
11 more elements
A disk drive comprising:
- a disk comprising a plurality of data tracks;
- a head actuated over the disk;
- and
- control circuitry coupled with the head operable to:
- write data to the plurality of data tracks;
- read a first data area of a first data track to generate a first read back signal;
- determine a first quality metric and a channel flag in response to the first read back signal;
- determine that the first quality metric exceeds a first threshold;
- apply additional stress to the first data area;
- reread the first data area to generate a second read back signal;
- determine a second quality metric in response to the second read back signal;
- and
- determine whether the second quality metric exceeds a second threshold, and
- wherein the control circuitry coupled with the head operable to apply additional stress to the first data area comprises control circuitry operable to apply additional stress to the first data area in response to the channel flag.
11 more elements
A disk drive comprising:
- a disk comprising a plurality of data tracks;
- a head actuated over the disk;
- and
- control circuitry coupled with the head operable to:
- write data to the plurality of data tracks;
- read a first data area of a first data track to generate a first read back signal;
- determine a first quality metric and a channel flag in response to the first read back signal;
- determine that the first quality metric exceeds a first threshold;
- apply additional stress to the first data area;
- reread the first data area to generate a second read back signal;
- determine a second quality metric in response to the second read back signal;
- and
- determine whether the second quality metric exceeds a second threshold, and
- wherein the control circuitry coupled with the head operable to apply additional stress to the first data area comprises control circuitry operable to write data to a second data area adjacent to the first data area in response to the channel flag.
11 more elements
A method of detecting a defect on a disk comprising:
- writing data to a plurality of data tracks on the disk;
- reading a first data area of a first data track to generate a first read back signal;
- determining a first quality metric and a channel flag in response to the first read back signal;
- determining that the first quality metric exceeds a first threshold and is below a third threshold;
- applying additional stress to the first data area;
- rereading the first data area to generate a second read back signal;
- determining a second quality metric in response to the second read back signal;
- and
- determining whether the second quality metric exceeds a second threshold.
6 more elements
A method comprising:
- writing data to a plurality of data tracks on the disk;
- reading a first data area of a first data track to generate a first read back signal;
- determining a first quality metric and a channel flag in response to the first read back signal;
- determining that the first quality metric exceeds a first threshold;
- applying additional stress to the first data area, wherein applying additional stress comprises applying additional stress in response to the channel flag;
- rereading the first data area to generate a second read back signal;
- determining a second quality metric in response to the second read back signal;
- and
- determining whether the second quality metric exceeds a second threshold.
6 more elements
A method comprising:
- writing data to a plurality of data tracks on the disk;
- reading a first data area of a first data track to generate a first read back signal;
- determining a first quality metric and a channel flag in response to the first read back signal;
- determining that the first quality metric exceeds a first threshold;
- applying additional stress to the first data area, wherein applying additional stress comprises writing data to a second data area adjacent to the first data area in response to the channel flag;
- rereading the first data area to generate a second read back signal;
- determining a second quality metric in response to the second read back signal;
- and
- determining whether the second quality metric exceeds a second threshold.
6 more elements
Dependencies are inferred from the claim text.