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

[Joe Julian]

On 09/01/2015 09:21 AM, Atin Mukherjee wrote:
>
> -Atin
> Sent from one plus one
> On Sep 1, 2015 9:39 PM, "Joe Julian" <joe at julianfamily.org 
> <mailto:joe at julianfamily.org>> wrote:
> >
> >
> >
> > On 09/01/2015 02:59 AM, Atin Mukherjee wrote:
> >>
> >>
> >> 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.
> >
> >
> > Again I ask, is this a departure from prior behavior?
> Not really, its there from long time. IIRC, this change was done when 
> quorum feature was introduced. KP can correct me.
>

Right, so unless server quorum is enabled, this shouldn't be the problem.

> >
> >
> >>>>> 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 
> <mailto: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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> >>>>>> http://www.gluster.org/mailman/listinfo/gluster-users
> >>>>>>
> >>>>>
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> >>>>>
> >>>
> >
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