On Tue, Jan 19, 2016 at 5:22 PM, lee <[email protected]> wrote: > "J. Roeleveld" <[email protected]> writes: > > How does that work? IIUC, when you created a snapshot, any changes you > make to the snapshotted (or how that is called) file system are being > referenced by the snapshot which you can either destroy or abandon. > When you destroy it, the changes you made are being applied to the > file system you snapshotted (because someone decided to use a very > misleading terminology), and when you abandon it, the changes are thrown > away and you end up with the file system as it was before the snapshot > was created. > > In any case, you do not get multiple versions (which only reference the > changes made) of the file system you snapshotted but only one current > version. > > Do you need to use a special file system or something which provides > this kind of multiple copies when you make snapshots? >
And that is exactly what zfs and btrfs provide. Snapshots are full citizens. If I create a snapshot of a directory in btrfs it is essentially indistinguishable from running cp -a on the directory, except the snapshot takes only seconds to create almost entirely regardless of size, and takes almost no space until changes are made. Later I can delete the snapshot, or delete the original, or keep both indefinitely making changes to either. -- Rich
