Method and apparatus for recovering parity protected data

Details Method and apparatus for recovering parity protected data Method and apparatus for recovering parity protected data

1992-11-12

1997-01-21

Baker, Stephen M.

G06F 1110, G06F 1120

Patent

active

055967094

ABSTRACT:
A storage management mechanism maintains parity records on the storage units it services, and includes a status map indicating, for each data block, the location of the corresponding parity block, and the status of the data block. If a single storage unit fails, the mechanism is placed in a failure operating mode while the system continues to operate. While in failure operating mode, storage management verifies status before accessing data on the failed storage unit. If the data has not yet been reconstructed, storage management first reconstructs the data block by successively reading and accumulating an Exclusive-OR of the corresponding blocks on all other storage units in the parity group. The reconstructed data block is then stored in the location of the parity block, and the status map is updated to indicate that the block has been reconstructed. Once the data has been reconstructed, it is only necessary to read from or write to the former parity block directly. Storage management will similarly reconstruct a block of storage on the failed unit before writing to any corresponding block on a non-failed unit, if the block has not yet been reconstructed. In an alternate embodiment, spare areas of storage in the non-failing storage units are allocated to the reconstructed data. The total of these spare areas constitute a virtual spare storage unit. As data is reconstructed, it is placed in the virtual spare unit, and parity is maintained in the normal fashion.

REFERENCES:
patent: 3893178 (1975-07-01), Sordello
patent: 4092732 (1978-05-01), Ouchi
patent: 4467421 (1984-08-01), White
patent: 4562576 (1985-12-01), Ratcliffe
patent: 4667326 (1987-05-01), Young et al.
patent: 4722085 (1988-01-01), Flora et al.
patent: 4754397 (1988-06-01), Varaiya et al.
patent: 4761785 (1988-08-01), Clark et al.
patent: 4768193 (1988-08-01), Takemae
patent: 4775978 (1988-10-01), Hartness
patent: 4817035 (1989-03-01), Timsit
patent: 4849929 (1989-07-01), Timsit
patent: 4870643 (1989-09-01), Bultman et al.
patent: 4899342 (1990-02-01), Potter et al.
patent: 4914656 (1990-04-01), Dunphy, Jr. et al.
patent: 4942579 (1990-07-01), Goodlander et al.
patent: 4989206 (1991-01-01), Dunphy, Jr. et al.
patent: 4993030 (1991-02-01), Krakauer et al.
patent: 5072378 (1991-12-01), Manka
patent: 5088081 (1992-02-01), Farr
patent: 5101492 (1992-03-01), Schultz et al.
patent: 5130992 (1992-07-01), Frey, Jr.
patent: 5134619 (1992-07-01), Henson et al.
patent: 5148432 (1992-09-01), Gordon et al.
Lee, E., "Software and Performance Issues in the Implementation of a RAID Prototype", Report No. UCB/CSD 90/573, Computer Science Division (EECS), University of California May 1990.
Invention Association Public Disclosure (Hatsumei Kyokai Kokai Giho) No. 85-14086.
Patterson et al; A Case for Redundant Arrays of Inexpensive Disks (RAID); Dept. of Elect. Engr. and Computer Sciences, Univ. of Cal. Berkeley, 1988 ACM 0-89791-268-3/88/006/0109, pp. 109-116.
Chen, P., Gibson, G., Katch, R. H., Patterson, D. A., and Schulze, M.; Introduction to Redundant Arrays of Inexpensive Disks (RAID) (Dec. 1988).
Chen, P., Gibson, G, Katz, R. H., Patterson, D. A., and Schulze, M. et al; Evolution of the Raid 2 Architecture (Jun. 12, 1990).
Maximum Strategy, Inc., San Jose, Calif; Strategy 2 Disk Array Controller Operation Manual (Nov. 2, 1988).
Maximum Strategy, Inc., San Jose, Calif.; Strategy 1 Disk Array Controller Operation Manual (Date unknown).
Gibson, G. A.; Performance and Reliability in Redundant Arrays of Inexpensive Disks (Date unknown).
Chen, P.; An Evolution of Redundant Arrays of Disks Using an Amdahl 5890; (May 1989).
Katz, R. H., Gibson, G. A., and Patterson, D. A.; Disk System Architectures for High Performance Computing (Mar. 1989).
Gray, J., Horst, B., and Walker, M.; Parity Striping of Disc Arrays: Low-Cost Reliable Storage with Acceptable Throughput (Jan. 1990).
Schultz, M. E.; Consideration in the Design of a Raid Prototype (Aug. 1988).
Clark, and Corrigan; IBM Systems Journal, vol. 23, No. 3, 1989.
Lawlor; Efficient Mass Storage Parity Recovery Mechanism; IBM Technical Disclosure Bulletin, vol. 24, No. 2, Jul. 1981, pp. 986-987 (Previously Submitted).
Anderson, M.; Strength (and Safety) in Numbers; BYTE, vol. 15, No. 13, Dec. 1990, pp. 337-339 (Previously Submitted).
Katz, R. et al; A Project on High Performance I/O Subystems; Computer Architecture News, vol. 17, No. 5, Sep. 1989, pp. 24-31 (Previously Submitted).
Patterson et al; A Case for Redundant Arrays of Inexpensive Disks (RAID).

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