The 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 file recovery of recently changed or deleted files. On our system, snapshots are enabled for the main filesystem (which includes the /admin, /course, /home, and /research directories). 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.

Using Snapshots

How you use the snapshots depends on whether you're using Windows or Unix.

For more information

See the Backups, Restores, and Snapshots page for more information.