Delayed initiation of read-modify-write parity operations in a raid level 5 disk array
US5388108A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 23, 1992 |
| Grant date | Feb 7, 1995 |
| Priority date | — |
| Expiry date | Oct 23, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F11/1008
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
An improved method for updating data and parity information in a RAID level 4 or 5 disk array employing a read-modify-write (RMW) process for updating data and parity information. During normal RMW operations, the old data and old parity information to be updated are read from disk, new parity is generated, and the new parity information and new data written to disk. The improved RMW method separates the execution of data read and write operations from the execution of parity read, generation and write operations to permit greater efficiency in the utilization of the drives within the array. The method identifies the disk drives containing the data and parity to be updated and places the proper read and write requests into the I/O queues for the identified data and parity drives, scheduling parity operations; i.e. reading old parity information from the parity drive, generating new parity information and writing the new parity information to the parity drive; for execution when best accommodated in the I/O queue for the parity drive, following the read of old data from the data drive.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.