[tahoe-dev] Potential use for personal backup

[Greg Troxel]

"Zooko Wilcox-O'Hearn" <zooko at zooko.com> writes:

> Dear Saint Germain:
>
> I think Tahoe-LAFS is best understood by (at least temporarily)
> forgetting all about a "filesystem", like ext3, zfs, etc. etc. Forget
> about that. It isn't a filesystem! (Until you get to the end of this
> letter.)
>
>
>  • Start by thinking of it as an application, like Bittorrent, which
> can be manually triggered to download a single file. (Bittorrent can
> only download—Tahoe-LAFS can also upload as well as download.) Or
> think of it as being more like "scp". You can run "scp $LOCALFILE
> $REMOTEHOST:$REMOTELOCATION", and you can run "tahoe put $LOCALFILE
> $DIRCAP/$GRIDLOCATION".

I find this a bit bizarre (but I'm one of those unix-heads you talk
about below).  But I think the reason I find it odd is that tahoe-lafs
*is* a filesystem.   Now, if you mean: "it's a filesystem, but think
about accessing a filesystem on another machine over scp; the current
software interface that people use feels more like that than mounting a
disk onto /mnt" then I see what you mean (and indeed it's true).

There are multiple separate issues in a filesystem:

  the fundamental API in terms of operations (not how the operations
  are expressed).  For things that act like a filesystem, this is
  somewhat constrained by culture.

  how the API is accessed (tahoe CLI vs integrated into OS VFS), which
  is much less important conceptually

  how the filesystem interacts with network/servers/etc. and storage
  representation (behind the abstraction boundary)

tahoe certainly has slightly unusual semantics compared to POSIX
(necessary because of how it works; that's not meant to be a complaint),
but in many ways it's not so far off.  On top of that there is a culture
of access via a command-line program or web gateway rather than OS
filesystem integration (as is normal for pretty much every other
filesystem), but I think that's both a current cultural artifact and a
reflection that the fuse support isn't complete/etc.



Also, I think 'tahoe backup' shouldn't be part of the tahoe command, as
the strategy of a backup program that works with any filesystem with
file-level deduplication is separate from tahoe-lafs proper.

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