Data storage system and method employing a write-ahead hash log
US6629198B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 8, 2000 |
| Grant date | Sep 30, 2003 |
| Priority date | — |
| Expiry date | Oct 15, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F11/1471
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A data storage system includes a computer coupled to a non-volatile storage, such as a disk drive. The computer includes a block cache for storing cached copies of data blocks, and a hash table that stores hash values corresponding to the data blocks. Prior to writing back a modified cache block to the non-volatile storage, a log recorder of the computer stores an updated hash value corresponding to the modified cache block within a write-ahead hash log, which is also contained in non-volatile storage. The log recorder creates a log record including an updated hash value and an address corresponding to a modified cache block. The log recorder additionally maintains a first pointer value indicative of log records that have been stored to the write-ahead hash log, and a second pointer value indicative of the most recent log record stored in the write-ahead hash log for which a corresponding modified cache block has been stored to the non-volatile storage. These pointer values are stored in the write ahead hash log with the log records. Log records are grouped into log blocks which are eventually written to the non-volatile storage as a group. After the log record containing the updat…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.