[tahoe-dev] Tahoe as glue filesystem

[Brian Warner]

> Man, it was great to hear you ask this question. The possibility of
> this for use in small, distributed, diskless devices is what most
> recently prompted me to take another look at tahoe. Of course I'm
> staying for the party anyway, but I am *deeply* interested in a
> memory- only option for tahoe.

Hm, I suppose it depends upon how much storage you have to work with. RAM or
flash? Swapping out the allmydata.storage module for something that keeps all
shares in a dictionary instead of in disk would be pretty easy.. we actually
have some test cases that do just that (to test upload/download code in
isolation from the storage code). But I think it would be hard to achieve
good reliability if your share integrity depends upon continuous power,
especially if the nodes are small (and likely to be portable or
battery-powered).


> As a follow-up to this question, Zooko (and I've done no background reading
> on this), is there any data replication in tahoe? If a host goes down and
> doesn't come back up, are file parts redistributed to the surviving nodes?

Not yet, but I'm starting work today on the "Repairer", which will take the
remaining shares of a file and produce enough new ones to bring it back up to
full-strength. There remains a question of when exactly to trigger this, but
the end result would be a lot like what you're talking about: surviving (or
brand-new) nodes wind up with parts of files that they didn't have before.

cheers,
 -Brian