[tahoe-dev] what should we work on at the Boulder Hack Fest?

Brian Warner warner at lothar.com
Thu Mar 29 18:22:44 UTC 2012

On 3/29/12 5:41 AM, Greg Troxel wrote:
> Your proposed plan sounds fine, but IMHO the biggest issue right now
> is the mutable-repair-increments-version problem.

Yeah, I concur.

I haven't looked at that code for a long time, but it occurs to me that
what it wants is a checker-results flag that says whether the unhealthy
status is due to the presence of multiple versions or not. In terms of
the ServerMap object, I think that's just:

 len(sm.recoverable_versions()) + len(sm.unrecoverable_versions()) > 1

We only need to do the full download+upload cycle (which increments the
version number) if there are multiple versions present. If we're just
missing a couple of shares (or some are corrupted and could be
replaced), then the number of versions ==1 and we should do a
non-incrementing form of repair.

I think we'll need new Repairer code to do that, though. Something to
set the new version equal to the existing version, to avoid sending
updates to existing correct shares, and something to make sure the
generated test-vectors are ok with all that. Not trivial, but not a huge
task either.


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