Hsieh T Hao

US Patent:

54126614, May 2, 1995

Filed:

Oct 6, 1992

Appl. No.:

7/957293

Inventors:

Hsieh T. Hao - Los Altos CA
Spencer W. Ng - San Jose CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 1110
G06F 1120

US Classification:

371 101

Abstract:

A data storage system architecture having an array of small data storage disks, organized into logical rows and columns, with each disk coupled to two disk controllers via two independent controller-disk interconnects. No two disks are coupled to the same pair of controllers. In this data storage system architecture, the component disks are arranged in parity groups of variable size. Within each parity group, failure of one disk sector can be recovered through data reconstruction using data from other disks in the parity group. One or more disks can be reserved as hot standbys for substitution on failure, automatically replacing any failing disk.

US Patent:

50688588, Nov 26, 1991

Filed:

Dec 21, 1989

Appl. No.:

7/455197

Inventors:

Miguel M. Blaum - San Jose CA
Hsieh T. Hao - Los Altos CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 1110

US Classification:

371 41

Abstract:

A method for implementing error-correcting codes for disks, wherein the statistics of error vary according to the radius of the location being accessed. A Reed-Solomon code is selected having data bytes and redundant bytes and an error-correcting capability sufficient to protect against an anticipated worst case or errors. The number of redundant bytes in that code, and thereby the number of correctable errors, is progressively reduced in respective concentric areas of the disk according to the statistics of error for such areas, for thereby progressively reducing the number of correctable errors as the need for error correction capability decreases. For multiband recording, the areas are concentric bands in each of which data is recorded at a clock frequency substantially proportional to its inner diameter; and in such case, the number of redundant bytes is reduced progressively in each successive band toward the innermost band. For conventional recording, the areas are concentric tracks recorded at substantially the same frequency; and in such case, the number of redundant bytes is reduced toward the outermost concentric area. This method may also be used to increase correction capability periodically when capability decreases, due for example to corrosion of a write-once optical disk.

US Patent:

52710122, Dec 14, 1993

Filed:

Feb 11, 1991

Appl. No.:

7/653596

Inventors:

Miguel M. Blaum - San Jose CA
Hsieh T. Hao - Los Altos CA
Richard L. Mattson - San Jose CA
Jaishankar M. Menon - San Jose CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 1110
G11B 2018

US Classification:

371101

Abstract:

A method and means for encoding data written onto an array of M synchronous DASDs and for rebuilding onto spare DASD array capacity when up to two array DASD fail. Data is mapped into the DASD array using an (M-1)*M data array as the storage model where M is a prime number. Pairs of simple parities are recursively encoded over data in respective diagonal major and intersecting row major order array directions. The encoding traverse covering a topologically cylindrical path. Rebuilding data upon unavailability of no more than two DASDs merely requires accessing the data array and repeating the encoding step where the diagonals are oppositely sloped and writing the rebuilt array back to onto M DASDs inclusive of the spare capacity.