Method for maintaining parity-data consistency in a disk array
US5533190A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Dec 21, 1994 |
| Grant date | Jul 2, 1996 |
| Priority date | — |
| Expiry date | Dec 21, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B20/1833
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method for assuring consistency between data and parity in a disk array system following a reset or a power failure condition which interrupts the execution of write I/O operations. The method includes the steps of: examining drive activities to identify unfinished write I/O operations due to an interrupt condition; logging information necessary to identify the unfinished operations and the array redundancy groups associated with the unfinished operations into a non-volatile memory; and checking for log entries in the non-volatile memory during a disk array subsystem initialization or the restoration of power. For each unfinished operation identified in the log, the method further includes the steps of: performing a bit-wise exclusive-OR of corresponding portions of the data stored within the associated redundancy group to calculate parity consistent therewith; and writing the calculated parity to the parity storage areas within the associated redundancy group. For an array operating with a failed disk drive member (i.e., in degraded mode), the method also logs information necessary to identify the storage areas to which the unfinished write I/O operations map new data and parity…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.