Handling copy on first write data for snapshot purposes
US8874524B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 22, 2012 |
| Grant date | Oct 28, 2014 |
| Priority date | — |
| Expiry date | May 3, 2033 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F2201/84
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A technique performs a write operation. The technique involves receiving, after a snapshot of a file system is taken, a write instruction to write new data to a particular portion of the file system. The technique further involves includes reading, in response to the write instruction, metadata to determine whether the new data is a first update of the particular portion since the snapshot was taken. The metadata identifies portions of the file system which have changed since the snapshot was taken. The technique further involves, when the new data is a first update of the particular portion since the snapshot was taken, copying the original data from cache memory (i.e., from the file system buffer cache) to snapshot storage (i.e., to a dedicated save area) and, after the original data is copied, updating the original data in the cache memory with the new data.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.