Method and apparatus for recovering parity protected data
US5596709A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 12, 1992 |
| Grant date | Jan 21, 1997 |
| Priority date | — |
| Expiry date | Nov 12, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F2211/104
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
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 embodimen…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.