Backups, Restores, and Snapshots

Since August 2010 we have been outsourcing our backups to Brown University Center for Computation and Visualization (CCV). An incremental backup is done nightly (ummm, sometimes it takes more than one day to complete a backup, but most days it only takes one day so this is mostly accurate!).

The GPFS file systems, main and data, are backed up nightly and ten copies are saved (if you never change a file it will always be available, but if you change it every day for ten days your changes before those ten days will not be available). The nbu filesystem is not backed up at all.

Restores

To request a restore please send email to problem@cs.brown.edu. Restore requests are queued and attended to within three days (we try to have them done for you as soon as possible). If there is a problem finding what you have requested, you will get a message requesting more information. It will speed the process up if you are as accurate about the window of time the restore can be done from as possible. Restores before August 2010 are no longer available.  When requesting a restore please remember the "10 copy" rule mentioned in the section above.

Snapshots (main filesystem)

 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 online 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; currently you can recover anything from the last three weeks. (Snapshots are not taken of the data or nbu filesystems.) This document will show you how this mechanism works and how to use it.

How do Snapshots 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 under /gpfs/main (/admin, /course, /home and /research all redirect to directories in /gpfs/main).

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.