Track-band squeezed-sector error correction in magnetic data storage devices
AssigneeHGST Netherlands B.V.
InventorsSridhar Chatradhi, Martin Aureliano Hassner, Kirk Hwang, Satoshi Yamamoto
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Abstract
Data storage devices using a two-level ECC scheme are described. Embodiments of the invention allow the recovery of sectors in a squeezed group of tracks in a that includes both a single track level ECC scheme and a track band ECC scheme that functions across the set of tracks in the band. The track band ECC scheme uses additional parity information calculated using input data from multiple tracks to allow correction across tracks.
Claims18
A data storage device that stores data in tracks that include a plurality of sectors of data, the data storage device comprising:
- a first-level error correction system that writes track parity information on each track in a selected band of tracks, the track parity information being calculated using a first mathematical algorithm using data stored on one track and performs error correction using the track parity information on a selected track when the selected track is read;
- and wherein the first-level error correction system detects unreadable sectors in the selected track and wherein the first-level error correction includes generating modified track parity data using readable sectors and skipping unreadable sectors;
- and
- a second-level error correction system that writes track band parity information for the selected band of tracks, the track band parity information being calculated using a second mathematical algorithm using data stored on the selected band of tracks and performs error correction using the track band parity information on a selected track band when the selected track band is read;
- and wherein the second-level error correction system performs error correction after the first-level error correction has completed and the second-level error correction includes generating modified track band parity data using readable and corrected sectors supplied by the first-level error correction system.
A method of operating a data storage device that stores data in tracks that include a plurality of sectors of data, the method comprising:
- performing a first-level error correction by writing track parity information on each track in a selected band of tracks, the track parity information being calculated using a first mathematical algorithm using data stored on one track and performing error correction using the track parity information on a selected track when the selected track is read;
- and wherein the first-level error correction includes detecting unreadable sectors in the selected track and generating modified track parity data using readable sectors and skipping unreadable sectors;
- and
- performing a second-level error correction by writing track band parity information for the selected band of tracks, the track band parity information being calculated using a second mathematical algorithm using data stored on the selected band of tracks and performing error correction using the track band parity information on a selected track band when the selected track band is read;
- and wherein the second-level error correction performs error correction after the first-level error correction has completed and the second-level error correction includes generating modified track band parity data using readable and corrected sectors supplied by the first-level error correction system.
Dependencies are inferred from the claim text.