Disc array apparatus checking and restructuring data read from a

Details Disc array apparatus checking and restructuring data read from a Disc array apparatus checking and restructuring data read from a

1997-05-06

2000-02-08

Baker, Stephen M.

Error detection/correction and fault detection/recovery

Pulse or data error handling

Digital data error correction

714 6, 714805, 714820, G06F 1110, G06F 1116

Patent

active

060237805

ABSTRACT:
The present invention relates to a disc array apparatus assuring that even if contradiction is detected in matching of parity data during a read parity check, correct host data is Restructured and can always be transferred to the host. The disc array apparatus of the present invention is particularly applicable to disc drives in the RAID configuration. For example, in a disc array apparatus of the present invention implementing RAID level 3, the disc array apparatus adds CRC data to data transferred from a host computer, divides the data, generates parity from the divided data, and stores the data and the parity data into the disc drives. During a read operation, the disc array apparatus of the present invention executes a read parity check. If contradiction is detected between the parity data stored in the disc drives and the parity data generated during the read parity check, the disc array controller sequentially assumes, one disc drive at a time, that one of the disc drives is storing erroneous data, restructures the host data from the divided data and parity data of the disc drives other than the disc drive storing erroneous data for each assumption, and executes a CRC check on the restructured host data for each assumption. Restructured host data is determined to be correct host data when the CRC check detects no error. The principle of the present invention is also implemented in other RAID levels, and using data such as time or counter value, to determine and restructure erroneous data.

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