[Gluster-users] Why is it not possible to mount a replicated gluster volume with one Gluster server?

[Atin Mukherjee]

On 09/01/2015 02:34 PM, Joe Julian wrote:
> 
> 
> On 08/31/2015 09:03 PM, Atin Mukherjee wrote:
>>
>> On 09/01/2015 01:00 AM, Merlin Morgenstern wrote:
>>> this all makes sense and sounds a bit like a solr setup :-)
>>>
>>> I have now added the third node as a peer
>>> sudo gluster peer probe gs3
>>>
>>> That indeed allow me to mount the share manually on node2 even if
>>> node1 is
>>> down.
>>>
>>> BUT: It does not mount on reboot! It only successfully mounts if
>>> node1 is
>>> up. I need to do a manual: sudo mount -a
>> You would need to ensure that at least two of the nodes are up in the
>> cluster in this case.
> 
> Atin, why? I've never had that restriction.
> 
> It sounds to me like the mount's trying to happen before any bricks are
> available and/or glusterd is listening.
In a 3 node cluster if two of the nodes are already down and the other
is rebooted then the GlusterD instance wouldn't start the brick process
until it receives the first handshake from one of its peer and for that
you would need your 2nd node to be up as well. This why its recommended
to have a 3rd dummy node (without any bricks) added to a existing 2 node
cluster.
> 
>>> Is there a particular reason for this, or is it a misconfiguration?
>>>
>>>
>>>
>>> 2015-08-31 21:01 GMT+02:00 Joe Julian <joe at julianfamily.org>:
>>>
>>>>
>>>> On 08/31/2015 10:41 AM, Vijay Bellur wrote:
>>>>
>>>>> On Monday 31 August 2015 10:42 PM, Atin Mukherjee wrote:
>>>>>
>>>>>>   > 2. Server2 dies. Server1 has to reboot.
>>>>>>   >
>>>>>>   > In this case the service stays down. It is inpossible to
>>>>>> remount the
>>>>>> share without Server1. This is not acceptable for a High Availability
>>>>>> System and I believe also not intended, but a misconfiguration or
>>>>>> bug.
>>>>>> This is exactly what I gave as an example in the thread (please read
>>>>>> again). GlusterD is not supposed to start brick process if its other
>>>>>> counter part hasn't come up yet in a 2 node setup. The reason it has
>>>>>> been designed in this way is to block GlusterD on operating on a
>>>>>> volume
>>>>>> which could be stale as the node was down and cluster was operational
>>>>>> earlier.
>>>>>>
>>>>> For two node deployments, a third dummy node is recommended to ensure
>>>>> that quorum is maintained when one of the nodes is down.
>>>>>
>>>>> Regards,
>>>>> Vijay
>>>>>
>>>> Have the settings changed to enable server quorum by default?
>>>>
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>>>
>>>
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> 
>