[Gluster-devel] [Gluster-users] VM fs becomes read only when one gluster node goes down

[André Bauer]

Thanks for the hints guys :-)

I think i will try to use an arbiter. As i use distributed / replicated
volumes i think i have to add 2 arbiters, right?

My nodes have 10GBit interfaces. Would be 1 GBit for the arbiter(s) enough?

Regards
André


Am 28.10.2015 um 14:38 schrieb Diego Remolina:
> I am running Ovirt and self-hosted engine with additional vms on a
> replica two gluster volume. I have an "arbiter" node and set quorum
> ratio to 51%. The arbiter node is just another machine with the
> glusterfs bits installed that is part of the gluster peers but has no
> bricks to it.
> 
> You will have to be very careful where you put these three machines if
> they are going to go in separate server rooms or buildings. There are
> pros and cons to distribution of the nodes and network topology may
> also influence that.
> 
> In my case, this is on a campus, I have machines in 3 separate
> buildings and all machines are on the same main campus router (we have
> more than one main router). All machines connected via 10 gbps. If I
> had one node with bricks and the arbiter in the same building and that
> building went down (power/AC/chill water/network), then the other node
> with bricks would be useless. This is why I have machines in 3
> different buildings. Oh, and this is because most of the client
> systems are not even in the same building as the servers. If my client
> machines and servers where in the same building, then doing one node
> with bricks and arbiter in that same building could make sense.
> 
> HTH,
> 
> Diego
> 
> 
> 
> 
> On Wed, Oct 28, 2015 at 5:25 AM, Niels de Vos <ndevos at redhat.com> wrote:
>> On Tue, Oct 27, 2015 at 07:21:35PM +0100, André Bauer wrote:
>>> -----BEGIN PGP SIGNED MESSAGE-----
>>> Hash: SHA256
>>>
>>> Hi Niels,
>>>
>>> my network.ping-timeout was already set to 5 seconds.
>>>
>>> Unfortunately it seems i dont have the timout setting in Ubuntu 14.04
>>> for my vda disk.
>>>
>>> ls -al /sys/block/vda/device/ gives me only:
>>>
>>> drwxr-xr-x 4 root root    0 Oct 26 20:21 ./
>>> drwxr-xr-x 5 root root    0 Oct 26 20:21 ../
>>> drwxr-xr-x 3 root root    0 Oct 26 20:21 block/
>>> - -r--r--r-- 1 root root 4096 Oct 27 18:13 device
>>> lrwxrwxrwx 1 root root    0 Oct 27 18:13 driver ->
>>> ../../../../bus/virtio/drivers/virtio_blk/
>>> - -r--r--r-- 1 root root 4096 Oct 27 18:13 features
>>> - -r--r--r-- 1 root root 4096 Oct 27 18:13 modalias
>>> drwxr-xr-x 2 root root    0 Oct 27 18:13 power/
>>> - -r--r--r-- 1 root root 4096 Oct 27 18:13 status
>>> lrwxrwxrwx 1 root root    0 Oct 26 20:21 subsystem ->
>>> ../../../../bus/virtio/
>>> - -rw-r--r-- 1 root root 4096 Oct 26 20:21 uevent
>>> - -r--r--r-- 1 root root 4096 Oct 26 20:21 vendor
>>>
>>>
>>> Is the qourum setting a problem, if you only have 2 replicas?
>>>
>>> My volume has this quorum options set:
>>>
>>> cluster.quorum-type: auto
>>> cluster.server-quorum-type: server
>>>
>>> As i understand the documentation (
>>> https://access.redhat.com/documentation/en-US/Red_Hat_Storage/2.0/html/A
>>> dministration_Guide/sect-User_Guide-Managing_Volumes-Quorum.html
>>> ), cluster.server-quorum-ratio is set to "< 50%" by default, which can
>>> never happen if you only have 2 replicas and one node goes down, right?
>>>
>>> Do in need cluster.server-quorum-ratio = 50% in this case?
>>
>> Replica 2 for VM storage is troublesome. Sahine just responded very
>> nicely to a very similar email:
>>
>>   http://thread.gmane.org/gmane.comp.file-systems.gluster.user/22818/focus=22823
>>
>> HTH,
>> Niels
>>
>> _______________________________________________
>> Gluster-users mailing list
>> Gluster-users at gluster.org
>> http://www.gluster.org/mailman/listinfo/gluster-users
> 


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André Bauer

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André Bauer
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