US 6,188,538 B1 · Retry off-track positioning table

Abstract

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.

Claims16

Dependent claims

A method for enhancing off-track recovery of data that has become unreadable to a data storage device, the device having a read head presentable to a data track on a storage medium, the method comprising:

(a) recording a set of data on the data track;
(b) detecting instances of data recorded in step (a) becoming unreadable by the device due to the read head not tracking the data as recorded on the data track;
(c) performing selected off-track reads so as to recover the unreadable data detected in step (b), each off-track read performed at an off-track position in a spectrum thereof across the data track;
(d) for each off-track position in the spectrum, counting the number of times that data is recovered from that off-track-position during step (c);
(e) ranking off-track positions into a series corresponding to incidents of data recovery counted in step (d), the series in order of the off-track position having most incidents down to the off-track position having least incidents;
(f) embodying the series in a table;
(g) loading the table into firmware on the device;
and
(h) following the table in future off-track read attempts by the device to recover unreadable data.

6 more elements

Dependencies are inferred from the claim text.

Retry off-track positioning table

Life of this patent

Retry off-track positioning table

Life of this patent

Abstract

Claims16