Methods of determining and searching for modified blocks in a file system
US7756844B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 23, 2008 |
| Grant date | Jul 13, 2010 |
| Priority date | — |
| Expiry date | Feb 9, 2029 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F2201/84
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
The invention relates to a method of determining if a block was modified in a file system by comparing the versions of the base snapshot, the delta snapshot, and the space map block entry (b, e). In another aspect, the invention relates to a method of searching for blocks modified in a tree structured file system. The invention relates to methods and systems of snapshot management of a file system in a data storage system. To represent the snapshots, the invention maintains pointers to the root block pointer of each snapshot. When the active file system is modified, this invention avoids overwriting any blocks used by previous snapshots by allocating new blocks for the modified blocks. When the invention needs to put an established block in a new location, it must update a parent block to point to the new location. The update to the parent block may then require allocating a new block for the new parent block and so forth. Parts of the file system not modified since a snapshot remain in place. The amount of space required to represent snapshots scales with the fraction of the file system that users modify. To maintain snapshot integrity, this invention keeps track of the first and …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.