Maintaining backups is possibly one of the more frustrating aspects of system administration. It consumes substantial resources such as storage media and storage devices, puts a noticeable burden on the fileservers while the backup is happening, requires regular monitoring, and occasional attention, but is comparatively rarely used to actually restore anything. Of course when a calamity does hit and you loose some data, you are very thankful for the backups.
If the filesystem can make backups less burdensome and more effective in any way, then it will make life easier for system administrators.
Three sorts of backups that we make at UNSW/CSE can be described as Calamity backups, Archival backups, and Carelessness backups. We will look at these in turn and see how the filesystem can help.