[sheepdog-users] Performance Impact of Recovery

[richter at ecos.de]

> >
> > So the question is how can this recovery process speed up?
> >
> 
> We have a patch to speed up recovery
> 
> * <efbf7f0> 2014-02-06 [Liu Yuan] sheep/recovery: multi-threading recovery
> process
> 
> which is merged in the master branch. I think this will speed up recovery
> process a lot and the more the disks you have, the better speed-up.
> 

I have 2 disks per node. I will give it a try.

> >
> > From my current knowledge (which is not too deep), the only idea would
> > be to calculate the data block hashes during storing of the data block
> > and compare only stored hashes. Would this be possible/make sense or
> > is there a better solution?
> 
> We already do it the way you suggested for full replication scheme.
> 

I do not use erasure coding (dog vdi list shows copies = 3), so it uses full
replication scheme, right?

Sheep finally finished the recovery after 9h of hard work. It recovered
about 150000 blocks. This is about 5Blocks/s and it had most the time
between 5-10MByte/s Readrate. So this looks to me that it is reading much
more data, then only the precomputed hashes. Do I have to use any special
option during startup (or compiling) or do I understand things completely
wrong?

Thanks & Regards

Gerald