Tux3: the other next-generation filesystem [LWN.net]

Tux3: the other next-generation filesystem

Posted Dec 2, 2008 23:04 UTC (Tue) by daniel (subscriber, #3181)
In reply to: Tux3: the other next-generation filesystem by aigarius
Parent article: Tux3: the other next-generation filesystem

One other common utility that Linux filesystem developers often forget is undelete - a tool that would analyse the filesystem and report what files and what versions of files it can recover. This should be simple enough to implement in Tux3.

It's on the to.do list. The standard argument against undelete is that it can be implemented at a higher level, as a move to a Trash folder in place of a delete. In practice, there is often not a gui around, and it doesn't help when you are running a shell under the gui. So if it turns out to be easy to do as part of the versioning, Tux3 will have it.

Regards, Daniel

(Log in to post comments)

Tux3: the other next-generation filesystem

Posted Dec 3, 2008 2:55 UTC (Wed) by rsidd (subscriber, #2582) [Link]

Doesn't Tux3 support snapshots (or won't it, in the future)? With snapshots you don't need undelete.

Tux3: the other next-generation filesystem

Posted Dec 3, 2008 7:23 UTC (Wed) by daniel (subscriber, #3181) [Link]

Snapshots do not take care of all undelete cases - you might not have taken a snapshot before deleting something important. But I am thinking in terms of using the snapshot mechanism to support undelete, essentially creating an "anonymous snapshot" just for the directory where the delete happened. This could be done without wasting a lot of space by using Tux3's versioned attribute model, which would avoid having to use a full disk block just to remember a single undeleted name.

Tux3: the other next-generation filesystem

Posted Dec 3, 2008 8:05 UTC (Wed) by rsidd (subscriber, #2582) [Link]

I've seen your email exchange with Matt Dillon on tux3 and hammer on the dragonfly lists some time back. Hammer can take snapshots at very fine-grained interval -- say every few minutes -- via a cron job and it is not very expensive (supposedly -- I haven't used it myself, yet). That would be incredibly useful. Undelete doesn't take care of all recovery requirements either -- you may have deleted text in a document that you later want back, for example. With hammer, just look at the snapshot from 2 minutes before you deleted it.

I suppose if you have a filesystem where many bulky files are being altered frequently, this is not a great idea, but you can tune the frequency of the snapshot and pruning (or disable snapshotting entirely, if need be...)