User:Rewood/AFS Backup info
Unlike common client backup utilities (HP Colorado Backup, et. al.), AFS backup operates on the volume and not on the files and directories that the volume contains. So, when backup runs, it archives the contents of the entire volume. This means, when you do a restore, you have to retore the entire volume. You can't easily pick and choose a file here, a dir tree there. AFS backup is capable of incremental backups, but even then it's archiving the changed files/dirs within a volume and still refers to the volumes as the defining characteristic of the backup run.
This is one reason why we limit volumes to 2 Gb. Anything larger and backup can encounter problems with timeouts, running out of time to archive before it's time to quit, etc.
Limiting vol size also helps when moving volumes from one AFS server to another.
Basic rule is, volumes are the fundamental type for AFS and everything is done with respect to the volume. That's why our locker model is built around the volume concept. The design stems out of AFS's inherent properties.