[Gluster-users] Automatic arbiter volumes on distributed/replicated volumes with replica 2?

André Bauer abauer at magix.net
Thu Mar 31 13:04:25 UTC 2016

OK, thanks.

As i understand, quorum does not work on a 2 node replica 2 cluster.
Thats the reason VM images get read only, if one node goes down.

To get it work you need replica 3 and therefore a full third node or at
least an arbiter.

Why is this also the case when having 4 node replica 2 cluster?

I use the other 2 nodes to have distributed/replicated volumes.
Imho this should be enough to get proper quorum?
If not, why?

Imho the distribution nodes could also do the work the arbiter does in
a 4 node replicated/distributed setup?
Is this something thats makes sense from a technical view?

If its technical possible but just no feature at the moment i would
really like to see this in the future.


Am 30.03.2016 um 03:15 schrieb Ravishankar N:
> On 03/30/2016 01:33 AM, André Bauer wrote:
>> Am 24.03.2016 um 13:56 schrieb Ravishankar N:
>>> On 03/24/2016 04:30 PM, André Bauer wrote:
>>>> So if you have a 4 node cluster is it realy needed to have a third
>>>> replica? Imho the 2 of the nodes could also be used as arbiters?
>>> I'm not sure I understand. The 'arbiter' volume is a special type of
>>> replica volume where the 3rd brick of that replica (for every replica)
>>> only holds metadata. So if you're asking if this brick itself can be
>>> co-located on a node which holds the other 'data' bricks of the volume,
>>> then yes that is possible.
>> My Question is:
>> If i have 4 Nodes and use replica 2, why should i need to add 2 more
>> arbiter nodes, when i also have 2 (distributed) nodes which could do the
>> arbiter job automaticly?
> Again, the term 'arbiter' is used to refer to a type of replica-3 volume
> in gluster parlance (at least until another feature comes that uses the
> same terminology ;-) ). A replica-2 configuration does not have an
> 'arbiter'.
>> Imho 4 nodes should be enough to get proper quorum even if only replica
>> 2 is used.
> There are both client and server quorums in gluster.
> http://gluster.readthedocs.org/en/latest/Administrator%20Guide/arbiter-volumes-and-quorum/
> has more information.
> Thanks,
> Ravi
>> Regards
>> André
>>> -Ravi
>>>> Does it make sense to open a feature request in the bugtracker?
>>>> Regards
>>>> André
>>>> Am 24.03.2016 um 11:02 schrieb Ravishankar N:
>>>>> On 03/24/2016 02:39 PM, André Bauer wrote:
>>>>>> Hi List,
>>>>>> we just upgraded out 4 node cluster from 3.5.8 to 3.7.8.
>>>>>> Because of replica 2 on all volumes i run into problems with read
>>>>>> only
>>>>>> file systems of vm images when running on 3.5.x. As i know now the
>>>>>> solution would be to have replica 3 or at least use arbiter volumes.
>>>>>> Yesterday i stumbled over this post in the list which i missed before
>>>>>> (damn spam filter):
>>>>>> https://www.gluster.org/pipermail/gluster-users/2015-November/024191.html
>>>>>> Steve Dainard is pointing out that 3.7.x uses an automatic arbiter,
>>>>>> when
>>>>>> you have 4 nodes configured as distributed/replicated.
>>>>>> Is this true? Could not find something about it in the documentation
>>>>>> :-/
>>>>> There is no 'automatic' arbiter for replica 2. I think he was
>>>>> referring
>>>>> to the dummy node peer probed for maintaining server quorum.
>>>>> -Ravi
>>>>>> Would be nice i could save on having 2 more nodes this way.
>>>>>> If not, is there a chance to see such feature in the future?

Mit freundlichen Grüßen
André Bauer

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André Bauer
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