Hewlett-Packard Company

John L Moore

Mark E Mills

Frame-based heroic data recovery on data retrieved from mass storage in which identifiable blocks have been detected to be corrupt. Logical sets of blocks are configured into frames. The invention becomes operable when standard data recovery techniques such as Error Correction Code (&ldquo;ECC&rdquo;), working on a frame-by-frame basis, are unable to recover all the corrupt data within the frame because there are just too many corrupt data blocks. The invention then sequentially applies a preselected series of heroic techniques, each heroic technique in the series applied concurrently to all blocks in the frame. The invention combines the corrective effects of the individual applications of heroic techniques in the series, until sufficient individual data blocks overall in the frame are recovered to allow standard frame-based recovery techniques such as ECC to complete the job.

Frame-based heroic data recovery

An improved heroic data recovery technique in which the inventive mechanism initially calibrates data storage devices' read/write mechanism misalignment characteristics and then reduces such calibration to an off-track positioning table. The table reflects a histogram indicating statistically where the misalignment is most likely to be found based on measurement of the characteristics of the device. The device's off-track positioning mechanism uses this table to execute a series of off-track read attempts in statistical order of likelihood of recovering unreadable data. The read head moves first to the off-track position in the table where statistically the misalignment is most likely to be found, and then to the next most likely, and so on, until the data is either found and recovered, or the series embodied in the table is exhausted. If the table becomes exhausted, an alternative heroic technique must be applied.

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Solvang, CA, United States of America

John L Moore