Electrical computers and digital processing systems: memory – Storage accessing and control – Hierarchical memories
Patent
1995-10-13
1998-06-30
Beausoliel, Jr., Robert W.
Electrical computers and digital processing systems: memory
Storage accessing and control
Hierarchical memories
39518204, 711114, 371 404, C06F 1110
Patent
active
057746435
ABSTRACT:
Disclosed is a method and apparatus for reconstructing data in a computer system employing a modified RAID 5 data protection scheme. The computer system includes a write back cache composed of non-volatile memory for storing (1) writes outstanding to a device and associated data read, and (2) storing metadata information in the non-volatile memory. The metadata includes a first field containing the logical block number or address (LBN or LBA) of the data, a second field containing the device ID, and a third field containing the block status. From the metadata information it is determined where the write was intended when the crash occurred. An examination is made to determine whether parity is consistent across the slice, and if not, the data in the non-volatile write back cache is used to reconstruct the write that was occurring when the crash occurred to insure consistent parity, so that only those blocks affected by the crash have to be reconstructed.
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Elkington Susan G.
Lubbers Clark E.
McLean Ronald H.
Baderman Scott T.
Beausoliel, Jr. Robert W.
Digital Equipment Corporation
Hudgens Ronald C.
Peterson Cathy L.
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