[tahoe-dev] Owncloud / Tahoe

Zooko O'Whielacronx zookog at gmail.com
Tue Apr 23 18:57:29 UTC 2013

On Tue, Apr 23, 2013 at 8:05 AM, Greg Troxel <gdt at ir.bbn.com> wrote:
> I am guessing that he wants file storage space under owncloud (which is among other things a fileserver) to be backed by tahoe (vs local disk vs some sort of cloud provider storage).
> The natural thing to do would be to mount a tahoe alias onto a VFS directory, and then use that mount point in owncloud.  But the tahoe project avoids that, and says it's better for users to use a special interface

I try to be specific about the reasons, when I say things like this.
Hopefully it can help people understand when my advice is applicable
and when it isn't.

The specific problem with accessing Tahoe-LAFS through a POSIX API is
that it might require uploading many copies of a file in order to
emulate the POSIX semantics. For example, imagine an app that opens a
large file, edits the last 20 bytes of the file, and closes it, over
and over. With the current Tahoe-LAFS POSIX emulation, this will
require uploading a complete copy of the entire file, no matter how
big it is, every time the app closes the file. This will probably lead
to a timeout, or at least be unusable, as well as filling up your
Tahoe-LAFS storage server with useless old copies.

Here's my latest attempt to document this in the FAQ, prompted by this


Anyway, I wouldn't be surprised if ownCloud has similar, or different,
impedance mismatches which prevent certain use cases from working
through FUSE with ownCloud, in which case whoever is using their apps
with ownCloud through FUSE could use them just as well with Tahoe-LAFS
through FUSE. So, if that guess is right, then this would be a case
where my specific warning against a POSIX emulation layer doesn't

But, I suppose this is all guesswork and imagination until someone
tries using it this way and reports back.

>   mount_tahoe ~/.tahoe:alias ~/tahoe-alias

Yeah, that would be great! If you want to track progress, or
contribute, that is ticket #1357.

https://tahoe-lafs.org/trac/tahoe-lafs/ticket/1357# 'tahoe mount' command



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