Creating point-in-time copies of file maps for multiple versions of a production file to preserve file map allocations for the production file
US8620973B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 25, 2012 |
| Grant date | Dec 31, 2013 |
| Priority date | — |
| Expiry date | Sep 25, 2032 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F16/128
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
To preserve the contiguity of file map extents of a production file when making a series of snapshot copies, the snapshots share indirect blocks of the production file through virtual pointers. When a write to a data block of the production file is first done since the time of the most recent snapshot so that the most recent snapshot can no longer share one of the contiguous indirect blocks, a new indirect block is allocated to store the file mapping metadata for the most recent snapshot, and a virtual pointer for the snapshots is changed to point to this new indirect block. Therefore the change in the virtual pointer changes the file mapping metadata for any number of snapshots sharing the new indirect block so that the method is scalable.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.