On 10/27/2015 10:54 PM, Nicolás wrote:
Hi,
We're using ovirt 3.5.3.1, and as storage backend we use GlusterFS. We
added a Storage Domain with the path "gluster.fqdn1:/volume", and as
options, we used "backup-volfile-servers=gluster.fqdn2". We now need
to restart both gluster.fqdn1 and gluster.fqdn2 machines due to system
update (not at the same time, obviously). We're worried because in
previous attempts, when restarted the main gluster node (gluster.fqdn1
in this case), all the VMs running against that storage backend got
paused due to storage errors, and we couldn't resume them and finally
had to power them off the hard way and start them again.
Gluster version on gluster.fqdn1 and gluster.fqdn2 is 3.6.3-1 (on
CentOS7).
Gluster configuration for that volume is:
Volume Name: volume
Type: Replicate
Volume ID: a2d7e52c-2f63-4e72-9635-4e311baae6ff
Status: Started
Number of Bricks: 1 x 2 = 2
Transport-type: tcp
Bricks:
Brick1: gluster.fqdn1:/gluster/brick_01/brick
Brick2: gluster.fqdn2:/gluster/brick_01/brick
Options Reconfigured:
storage.owner-gid: 36
storage.owner-uid: 36
cluster.server-quorum-type: server
cluster.quorum-type: none
network.remote-dio: enable
cluster.eager-lock: enable
performance.stat-prefetch: off
performance.io-cache: off
performance.read-ahead: off
performance.quick-read: off
Supported configuration for gluster storage domain in oVirt is replica 3
(echoing what Nir mentioned in ovirt users)
With "cluster.server-quorum-type: server" and a replica 2 setup,
bringing down one of the nodes will cause bricks on the remaining server
to be shut down too, and will cause VMs to pause.
We strongly advise you to use a replica 3 configuration or an arbiter
volume
(http://gluster.readthedocs.org/en/release-3.7.0/Features/afr-arbiter-volumes/)
If adding an additional server is not an option, you could try this for
present scenario -
1. turn off server quorum
2. Put host to maintenance in oVirt - and bring down gluster processes
on host
3. perform maintenance activity
4. Trigger self-heal and wait for it complete
5. Put second host to maintenance in oVirt and repeat process
We would like to know if this configuration should work, or if there's
something missing or some problem with the above specified version, as
pausing the VMs is a way to make it not fail but is not affordable for
us. Also, we've noted that the self-healing process takes *a lot* of
time, the above specified volume is 6T and it might take hours to
synchronize after a half-hour desynchronization.
The sharding feature available in gluster 3.7 will help with heal times.
Promising results have been reported by other users - minutes as opposed
to hours.
Any hints are appreciated,
Thanks.
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