[ovirt-users] hyperconverged question

Fri Sep 1 06:13:21 UTC 2017

To the OP question, when you set up a gluster storage domain, you need to
specify backup-volfile-servers=<server2>:<server3> where server2 and
server3 also have bricks running. When server1 is down, and the volume is
mounted again - server2 or server3 are queried to get the gluster volfiles.

@Jim, if this does not work, are you using 4.1.5 build with libgfapi
access? If not, please provide the vdsm and gluster mount logs to analyse

If VMs go to paused state - this could mean the storage is not available.
You can check "gluster volume status <volname>" to see if atleast 2 bricks
are running.

On Fri, Sep 1, 2017 at 11:31 AM, Johan Bernhardsson <johan at kafit.se> wrote:

> If gluster drops in quorum so that it has less votes than it should it
> will stop file operations until quorum is back to normal.If i rember it
> right you need two bricks to write for quorum to be met and that the
> arbiter only is a vote to avoid split brain.
>
>
> Basically what you have is a raid5 solution without a spare. And when one
> disk dies it will run in degraded mode. And some raid systems will stop the
> raid until you have removed the disk or forced it to run anyway.
>
> You can read up on it here: https://gluster.readthedocs.io/en/latest/
> Administrator%20Guide/arbiter-volumes-and-quorum/
>
> /Johan
>
> On Thu, 2017-08-31 at 22:33 -0700, Jim Kusznir wrote:
>
> Hi all:
>
> Sorry to hijack the thread, but I was about to start essentially the same
> thread.
>
> I have a 3 node cluster, all three are hosts and gluster nodes (replica 2
> + arbitrar).  I DO have the mnt_options=backup-volfile-servers= set:
>
> storage=192.168.8.11:/engine
> mnt_options=backup-volfile-servers=192.168.8.12:192.168.8.13
>
> I had an issue today where 192.168.8.11 went down.  ALL VMs immediately
> paused, including the engine (all VMs were running on host2:192.168.8.12).
> I couldn't get any gluster stuff working until host1 (192.168.8.11) was
> restored.
>
> What's wrong / what did I miss?
>
> (this was set up "manually" through the article on setting up self-hosted
> gluster cluster back when 4.0 was new..I've upgraded it to 4.1 since).
>
> Thanks!
> --Jim
>
>
> On Thu, Aug 31, 2017 at 12:31 PM, Charles Kozler <ckozleriii at gmail.com>
> wrote:
>
> Typo..."Set it up and then failed that **HOST**"
>
> And upon that host going down, the storage domain went down. I only have
> hosted storage domain and this new one - is this why the DC went down and
> no SPM could be elected?
>
> I dont recall this working this way in early 4.0 or 3.6
>
> On Thu, Aug 31, 2017 at 3:30 PM, Charles Kozler <ckozleriii at gmail.com>
> wrote:
>
> So I've tested this today and I failed a node. Specifically, I setup a
> glusterfs domain and selected "host to use: node1". Set it up and then
> failed that VM
>
> However, this did not work and the datacenter went down. My engine stayed
> up, however, it seems configuring a domain to pin to a host to use will
> obviously cause it to fail
>
> This seems counter-intuitive to the point of glusterfs or any redundant
> storage. If a single host has to be tied to its function, this introduces a
> single point of failure
>
> Am I missing something obvious?
>
> On Thu, Aug 31, 2017 at 9:43 AM, Kasturi Narra <knarra at redhat.com> wrote:
>
> yes, right.  What you can do is edit the hosted-engine.conf file and there
> is a parameter as shown below [1] and replace h2 and h3 with your second
> and third storage servers. Then you will need to restart ovirt-ha-agent and
> ovirt-ha-broker services in all the nodes .
>
> [1] 'mnt_options=backup-volfile-servers=<h2>:<h3>'
>
> On Thu, Aug 31, 2017 at 5:54 PM, Charles Kozler <ckozleriii at gmail.com>
> wrote:
>
> Hi Kasturi -
>
> Thanks for feedback
>
> > If cockpit+gdeploy plugin would be have been used then that would have
> automatically detected glusterfs replica 3 volume created during Hosted
> Engine deployment and this question would not have been asked
>
> Actually, doing hosted-engine --deploy it too also auto detects
> glusterfs.  I know glusterfs fuse client has the ability to failover
> between all nodes in cluster, but I am still curious given the fact that I
> see in ovirt config node1:/engine (being node1 I set it to in hosted-engine
> --deploy). So my concern was to ensure and find out exactly how engine
> works when one node goes away and the fuse client moves over to the other
> node in the gluster cluster
>
> But you did somewhat answer my question, the answer seems to be no (as
> default) and I will have to use hosted-engine.conf and change the parameter
> as you list
>
> So I need to do something manual to create HA for engine on gluster? Yes?
>
> Thanks so much!
>
> On Thu, Aug 31, 2017 at 3:03 AM, Kasturi Narra <knarra at redhat.com> wrote:
>
> Hi,
>
>    During Hosted Engine setup question about glusterfs volume is being
> asked because you have setup the volumes yourself. If cockpit+gdeploy
> plugin would be have been used then that would have automatically detected
> glusterfs replica 3 volume created during Hosted Engine deployment and this
> question would not have been asked.
>
>    During new storage domain creation when glusterfs is selected there is
> a feature called 'use managed gluster volumes' and upon checking this all
> glusterfs volumes managed will be listed and you could choose the volume of
> your choice from the dropdown list.
>
>     There is a conf file called /etc/hosted-engine/hosted-engine.conf
> where there is a parameter called backup-volfile-servers="h1:h2" and if one
> of the gluster node goes down engine uses this parameter to provide ha /
> failover.
>
>  Hope this helps !!
>
> Thanks
> kasturi
>
>
>
> On Wed, Aug 30, 2017 at 8:09 PM, Charles Kozler <ckozleriii at gmail.com>
> wrote:
>
> Hello -
>
> I have successfully created a hyperconverged hosted engine setup
> consisting of 3 nodes - 2 for VM's and the third purely for storage. I
> manually configured it all, did not use ovirt node or anything. Built the
> gluster volumes myself
>
> However, I noticed that when setting up the hosted engine and even when
> adding a new storage domain with glusterfs type, it still asks for
> hostname:/volumename
>
> This leads me to believe that if that one node goes down (ex:
> node1:/data), then ovirt engine wont be able to communicate with that
> volume because its trying to reach it on node 1 and thus, go down
>
> I know glusterfs fuse client can connect to all nodes to provide
> failover/ha but how does the engine handle this?
>
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