[Gluster-users] 3.7 Arbiter and/or quorum

[Ravishankar N]

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.
-Ravi
>
> 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`.
>>
>> HTH,
>> Ravi
>> 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 
>> 3.7
>>
>> - 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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