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

[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?
>>>>>
>>>>>
>>>>
>>
>>
>