Deferred copy-on-write of a snapshot
US6748504B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 15, 2002 |
| Grant date | Jun 8, 2004 |
| Priority date | — |
| Expiry date | Dec 8, 2022 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S707/99953
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A system, method and computer readable medium for deferring copy-on-write of a snapshot is disclosed. The method includes the generation of snapshot of a source file. Upon modification of a first data block referenced by the source file, the first data block is referenced by the snapshot and a second data block is allocated for the source file. Then, a first variable associated with the source file is set to a value indicating an incomplete source file data block and a second variable associated with the source file is set to a value indicating the valid portion of the second data block. Any portion of the second data block that is overwritten is considered valid. The second data block is then modified and the second variable is changed to reflect the modification. Upon reception of a read request, the corresponding portion of the second data block is retrieved.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.