[tahoe-dev] Questions

[Zooko O'Whielacronx]

You ask good questions. First you asked for some features that we
already have, then you asked for a couple of things that we don't have
but hopefully will soon...

On Wed, May 12, 2010 at 2:24 PM, Jason Wood <jwood275 at googlemail.com> wrote:
> This keeps getting better and better! That is exactly what I was hoping to
> hear!
> Ok, so it seems to do everything I need, now for a couple of questions about
> "nice to have" features...
> I believe I can set up a grid to consist of nodes on a LAN and WAN as part
> of the same storage cluster. So, if I had 3 locations each with 5 storage
> nodes, could I configure the grid to ensure a file is written to each
> location so that I could handle all servers at a particular location going
> down?

This is #467 and #573. In my mind these tickets are super-important:
they are one of the most frequently requested features from new users
or from people considering using Tahoe-LAFS. I imagine they could open
up new use cases for Tahoe-LAFS. On the other hand, these users who
request this so far haven't stuck around and kept requesting it with
increasingly precise comments on the tickets, so I'm not 100% sure if
we would be doing it right. Or maybe it turns out to be something that
people don't need as much as they thought they would.

> And finally, is it possible to modify a mutable file by "patching" it? So,
> if I have a file stored and I want to update a section of the file in the
> middle, is that possible or would be file need to be downloaded, patched and
> re-uploaded? I think I'm asking a lot here and I already have a plan to work
> around it but as the system seems to do everything else I need I figured it
> was worth asking.

It currently downloads the whole mutable file, holds the whole thing
in your RAM, patches it, then uploads the whole thing again. Bleah.

Documentation of this performance issue:

http://tahoe-lafs.org/trac/tahoe-lafs/browser/docs/performance.txt

Ticket: #393

This is a GSoC project featuring the excellent Kevan Carstensen in the
role of student and the excellent Brian Warner in the role of mentor!

So I fully expect this to be greatly improved by the Tahoe-LAFS v1.8
release in August of this year. :-)

Regards,

Zooko

http://tahoe-lafs.org/trac/tahoe-lafs/ticket/393# mutable: implement MDMF
http://tahoe-lafs.org/trac/tahoe-lafs/ticket/467# allow the user to
specify which servers a given gateway will use for uploads
http://tahoe-lafs.org/trac/tahoe-lafs/ticket/573# Allow client to
control which storage servers receive shares