Computer disk management system using doublet A-B logging
US6298425A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 12, 1999 |
| Grant date | Oct 2, 2001 |
| Priority date | — |
| Expiry date | Jan 12, 2019 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S707/99955
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Updating a single block of metadata is optimized into a single I/O operation. Resilience against single block failure and system crashes with a single or less than three I/O operations is provided. The present invention method and apparatus stores two copies of the metadata in two areas on disk. Each individual block of metadata in each area is duplicated as a doublet. The doublet provides two copies of a subject block to be written to disk as a single I/O. This enables metadata to survive a single block failure since such a failure only affects half of the doublet. Further, each block of metadata has header information including an indication of transaction and a part count. A transaction is not deemed committed until corresponding blocks of all parts are found.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.