rename "tahoe backup" to "tahoe snapshot"

[zooko]

tahoe backup is a good tool! It does a really cool thing. However, it doesn't do "backup". Proof: there is no tahoe restore. If you were try to simulate "restore" by running tahoe cp -r, it would be unable to do all sorts of things that you expect from a backup-and-restore program, such as restoring symlinks, restoring mtime and ctime, restoring uid and gid, or delta-compressing between subsequent versions.

Maybe we should rename tahoe backup to tahoe snapshot. Then people who want backup would stop complaining that tahoe backup is a crummy backup tool, they would start using a good backup tool (such as duplicati+Tahoe-LAFS), and they would start using the newly created tahoe snapshot tool for its cool snapshot-making behavior.

See comment:13:ticket:1946, comment:14:ticket:1946.

[zooko]

mailing list thread

[daira]

I'd much rather enhance tahoe backup to record more metadata (and to tolerate errors better), and add a tahoe restore (or tahoe cp --restore) command to restore that metadata. I think that tahoe backup is a good idea for backups because:

• it makes effective use of immutable files and directories;
• I like the transparency of a backup being a snapshot rather than some opaque thing in some weird format I don't understand, as it is for most backup programs.

[ClashTheBunny]

Replying to daira:

I'd much rather enhance tahoe backup to record more metadata (and to tolerate errors better), and add a tahoe restore (or tahoe cp --restore) command to restore that metadata.

I think that this would be nice for many reasons, including making Tahoe-LAFS more of a file system and less just an object store.

• I like the transparency of a backup being a snapshot rather than some opaque thing in some weird format I don't understand, as it is for most backup programs.

From the Duplicati website:

Duplicati is built using standard tools and formats. Un-encrypted archives are simple .zip archives. Encrypted archives are .zip archives that can be decrypted with AES Crypt. So, even without Duplicati all your data are belong to you :-)

And from duplicaty's webiste:

Standard file format: Athough archive data will be encrypted, inside it is in standard GNU-tar format archives. A full backup contains normal tarballs, and incremental backups are tar archives of new files and the deltas from previous backups. The deltas are in the format produced by librsync's command-line utility rdiff.

Although you should never have to look at a duplicity archive manually, if the need should arise they can be produced and processed using GnuPG, rdiff, and tar.

[zooko]

Replying to daira:

I'd much rather enhance tahoe backup to record more metadata

But, even after someone does that, mightn't people still want a tahoe snapshot that doesn't record more metadata, for the other use case?

[daira]

See also #1325 (make tahoe backup keep more filesystem metadata).

[daira]

Replying to zooko:

But, even after someone does that, mightn't people still want a tahoe snapshot that doesn't record more metadata, for the other use case?

See #658 ("tahoe cp" should avoid full upload/download when the destination already exists (using backupdb and/or plaintext hashes)).

[daira]

... and #835 ("tahoe cp -r --mutable/--immutable": make mutable copy of immutable directories or vice versa).

I wouldn't be averse to having tahoe snapshot be an alias for, say, tahoe cp -r --immutable --use-backupdb.

[ambimorph]

I just went through a similar experience as described in ​Taylor's S4 Usability Notes for the tahoe-LAFS part in terms of managing the interfaces (both web and command line), and trying to not so much *restore* but even *find* the files that I backed up. I independently discovered this same discussion about backup vs. snapshot, and tahoe cp -r.

I now don't understand why I would ever use backup instead of cp -r, if I want to be able to navigate the files later. It also took me a long time to figure out how to get the top level directory included in the cp, by repeating the name of it after the alias.