IntroductionThe CS Department uses a GPFS (General Parallel File System) file server to provide network file service to both Unix and Windows clients. This server has a feature known as snapshots which allows for online file recovery of recently changed or deleted files. This document will show you how this mechanism works and how to use it.
How does it work?
A snapshot is a read-only copy of all the files and directories in the
filesystem. The server creates a snapshot every four hours. Snapshots can be
accessed as quickly and easily as the live filesystem from the
.snapshots directory in every directory.
Snapshot directories are named for the (GMT) time the snapshot was taken. On disk we keep the most recent six snapshots, the last seven snapshots taken at midnight, and the last four snapshots taken at midnight on Sundays. This means that the live filesystem will have backups going back about a month.
The snapshot mechanism is independent of our normal tape backup mechanism, which goes much further back.