[ovirt-users] hyperconverged question

Fri Sep 1 06:01:30 UTC 2017

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/Ad
ministrator%20Guide/arbiter-volumes-and-quorum/
/JohanOn 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 
> m> 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 
> > om> 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 
> > > > il.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 
> > > > > .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 
> > > > > > @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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> > > > > > > 
> > > > > > 
> > > > > 
> > > > 
> > > 
> > 
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