The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 30, 1998
Filed:
Oct. 13, 1995
Clark E Lubbers, Colorado Springs, CO (US);
Susan G Elkington, Colorado Springs, CO (US);
Ronald H McLean, Elbert, CO (US);
Digital Equipment Corporation, Maynard, MA (US);
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.