Snapshot

Snapshotting is the name for two modes: snapshotting a filesystem and snapshotting an OS. The latter is allowed with virtualization software such as vmware which takes the state of the OS and its filesystems and saves it to disk so that it can be continued later.

Snapshotting a filesystem is found in ffs, hammer filesystem and zfs. It allows a realtime copy of a filesystem which then keeps files that are changed on teh real filesystem the same as before so that perhaps a clean backup can be done without files changing.