Backup directory for a write cache
US6119209A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 3, 1998 |
| Grant date | Sep 12, 2000 |
| Priority date | — |
| Expiry date | Feb 3, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F12/0895
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
For error recovery purposes, a backup copy of only a portion of the cache directory is maintained in non-volatile storage. Because only a portion of the cache directory is backup copied, a savings in storage space is realized. The partial copy includes an indication of the storage locations on a storage device for which data is in the cache, and an indication of the state of the data, i.e., whether the data is in process of being read from the cache by the processor, is in process of being written to the cache by the processor, is in the process of being destaged from the cache to the storage device, or none of the above. Only certain changes to the state of the cache cause a backup copy of a portion of the cache directory to be saved; other changes to the state of the cache do not cause the portion of the cache directory to be saved in non-volatile storage. This saves processing time by limiting the number of times that data is copied to the cache.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.