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Re: fsfs revprop packing in f5 Re: Does fsfs revprop packing no longer allow usage of traditional backup software?

From: Daniel Shahaf <danielsh_at_elego.de>
Date: Thu, 7 Jul 2011 16:33:24 +0300

Hyrum K Wright wrote on Thu, Jul 07, 2011 at 08:29:31 -0500:
> On Thu, Jul 7, 2011 at 2:36 AM, Philip Martin
> <philip.martin_at_wandisco.com> wrote:
> >
> > r0 revprops are a concern, they can have different access patterns.  For
> > example a master/slave setup running svnsync once per revision (a common
> > setup) will write the r0 pack file several times per revision.  We don't
> > want the pack file to become the dominant IO.
> >
> > I wonder if we could offset the shard boundaries, so that r0 is the last
> > revision in the first shard and r1-rN is the second shard.  Then r0
> > would be a shard on its own and the r0 pack file would be much smaller.
> > We would have to repack the repository on upgrade but the code changes
> > for this could be small, just +/-1 in a few places.
>
> Changing the offsets for all the shard boundaries is just asking for
> trouble, as it would mean that revision shards and revprop shards
> wouldn't match up. That seems like a pretty big "gotcha".
>
> Instead, we could just special-case r0 revprops so that they never get
> packed, and that the 0th shard includes r1:rN, instead of r0:rN. That
> would only impact the 0th shard, rather than every revprop shard.
>

+1
Received on 2011-07-07 15:37:25 CEST

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