[Users] Re: openvz with OCFS2

[Tim Small]

On 11/01/11 08:13, Aleksandar Ivanisevic wrote:
> "Frank" <frank at si.ct.upc.edu> writes:
>
>   
>> We use pacemaker to start/stop VEs and to be sure they only run on one
>> node. Anyway crashes happen periodicly. We have about 40 VEs
>> distributed
>>     
> Pacemaker is nice, but if it fails (think split brain), there is
> really nothing to prevent data loss.
>
> How do you handle split brain on a shared volume when you have half of
> VEs running on each side?
>   

That's unlikely with our topology (one half of the split is likely to
have no connectivity, and therefore the changes there can be discarded),
and we would do manual split brain recovery if necessary (haven't had to
yet).

We don't currently use drbd in multi-master mode, instead we have a
number of drbds per node pair, and all the VEs associated with a given
drbd must run on the same node at the same time.

Another way to solve the problem would be to use similar methods to
OCFS2 etc. (AFAIK) i.e. corosync instead of heartbeat (and use more than
two nodes in your corosync totem ring) and set your quorum to prevent
split-brain occurring at all.

Cheers,

Tim.


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