Error correction with on-demand parity sectors in magnetic data storage devices

摘要

Data storage devices are described with an ECC system that generate additional on-demand ECC information for a previously written track to provide for correction of data errors in the track and thereby avoid having to rewrite the track. Embodiments of the invention address the squeeze-error problem that arises when writing the next (second) track in a sequence causes errors to be introduced in the adjacent previously written (first) track. In alternative embodiments the existence of the data errors in the first track can be detected by reading the track or by estimating the number of likely errors using head position data measured while writing the first and second tracks. The additional on-demand ECC information can be written on any track that is available.

主权项

1. A data storage device that stores data in a region on a disk in a plurality of tracks that include a plurality of sectors of data, the data storage device comprising:
a track-level error correction system that writes a first set of parity sectors on a selected first track on the disk in addition to a first set of sectors of data, the first set of parity sectors being calculated using the first set of sectors of data stored in a memory; and an on-demand error correction system that determines a number of data sector errors in the first set of sectors of data on the first track after an adjacent second track has been written, and responsive to the number exceeding a selected threshold value, writes a second set of parity sectors calculated using the first set of sectors of data stored in the memory, and wherein the second set of parity sectors is written on a selected third track that is different from the selected first track.