[Gluster-users] 3.7 Arbiter and/or quorum
ravishankar at redhat.com
Thu Jul 16 01:50:07 UTC 2015
On 07/15/2015 10:54 PM, Scott Harvanek wrote:
> Using the virt group which does-
> cluster.quorum-type: auto
> cluster.server-quorum-type: server
> And from my understanding this means that quorum enforcement is
> enabled, and that it's brick related so if I only have two bricks then
> I cannot achieve 51% and split brain is likely even with a third node
> in the pool. If I move to fixed 1, then the likelihood of splitbrain
> is high.
In a replica 2 setup, if you set cluster.quorum-type to auto, you can
avoid split-brains in AFR. But the first brick must be up at all times.
> So what do I do here, get a fourth node and do distributed
> replicated? Trying to find the best performance option while
> minimizing split brain potential and I'm stuck with 3.6 clients (
> RHEV-H ) so the aforementioned arbiter is out, Replica 3 just seems to
> be a pig on the client side due to the triple write.
> Scott H.
>> Ravishankar N <mailto:ravishankar at redhat.com>
>> July 15, 2015 at 1:09 PM
>> On 07/15/2015 09:22 PM, Scott Harvanek wrote:
>>> I saw Ravi mention something earlier about the new arbiter volumes
>>> in 3.7
>>> - Can you run a arbiter 3.7 server volume with 3.6 clients? Or does
>>> this not work?
>> Unfortunately, no. This is because the logic for the feature is
>> mostly in the AFR translator which is loaded on the client process
>> (with some minor logic in the arbiter translator loaded on the brick
>> process). So both clients and servers need to be 3.7.
>>> Quorum question -
>>> - 3.6 server and clients, replica 2, however there's three+ servers
>>> in the cluster ( gluster pool list ). If one of the replicas fail
>>> is quorum maintained via the other servers in the cluster even
>>> though they are not part of the volume?
>> That would depend on what type of quorum is enabled (client or server
>> side). Each type has a different impact. You can look for the meaning
>> of cluster.quorum-type, cluster.quorum-count (these are client side
>> quorum options, applicable only to replicate volumes) and
>> cluster.server-quorum-type, cluster.server-quorum-ratio (these are
>> server side quorum options; they are not specific to replicate
>> volumes) in 'gluster volume set help`.
>> Scott Harvanek <mailto:scott.harvanek at login.com>
>> July 15, 2015 at 11:52 AM
>> I saw Ravi mention something earlier about the new arbiter volumes in
>> - Can you run a arbiter 3.7 server volume with 3.6 clients? Or does
>> this not work?
>> Quorum question -
>> - 3.6 server and clients, replica 2, however there's three+ servers
>> in the cluster ( gluster pool list ). If one of the replicas fail is
>> quorum maintained via the other servers in the cluster even though
>> they are not part of the volume?
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