[Sheepdog] How to know if sheepdog is recovering chunks

[MORITA Kazutaka]

At Thu, 1 Sep 2011 09:54:12 +0200,
Valerio Pachera wrote:
> 
> During my speedtests, I removed from the cluster a node and inserted
> it again several times.
> My cluster has 3 nodes and --copies=2.
> 
> When node3 was down I could see network and disks activity from atop but
>   collie cluster info
> doesn't give any clue if there is a sync/rebuild on the way.
> 
> In a previous discussion we said it's not a good idea to insert back a
> node while a syncronization is on.
> So
> 1) is there a way to be sure no sync are woking?

No.  The only way is to look at sheep.log carefully.  I guess we
should add a detail option to "collie cluster info".

I posted some patches to stabilize a node membership change.  Perhaps,
node additions during synchronization works well now on your
environment.

> 
> Looking at atop during the sync after node3 is gone off, I noticed
> that 'si' and 'so' (byte in and byte out the netwrok card) were most
> of the time 10Mbps and 10Mbps.
> Sometime they were up to 50si 10so or viceversa.
> Disks were realy not so busy (I don't remeber now but less than 50%
> read or write sure).
> 
> Node1 and node2 are connected by gigabit link so I was aspecting to
> see much more activity.
> 
> From the other side, if the sync process use too much resources, you
> mught ght I/O error on the guests.
> 2) does sheepdog limit the sync speed? If yes, is it possible the set
> the sync speed?
> e.g. I know drbd allow to set the sync speed limit.

No, but it is one of the important features.  I'd like to support it
in future.

Thanks,

Kazutaka