For those of you unfamiliar with them, the part of the reason the Network Appliance (NetApp) Filers became so popular (besides their speed and ease of administration) is the ability to create a filesystem snapshot. A filesystem snapshot is a point in time copy of the filesystem state (done with filesystem metadata). Snapshots are incredibly efficient to create (they use a small portion of the disk), and very easy to restore from. For example on a NetApp with a snapshot of vol0, you would cd to /vol0/.snapshot/snapshotname/directory and copy (yes that’s right copy) the file from the snapshot back to the desired location on disk. Pretty easy right?
FreeBSD now support filesystem snapshots with UFS2 based filesystems (see: FreeBSD UFS2 Snapshots Management Environment. I need to start upgrading some of my servers to FreeBSD 5.0 to exploit this functionality.