Hey All -

So I havent tested this yet but what I do know is that I did setup backupvol option when I added the data gluster volume, however, mount options on mount -l do not show it as being used

n1:/data on /rhev/data-center/mnt/glusterSD/n1:_data type fuse.glusterfs (rw,relatime,user_id=0,group_id=0,default_permissions,allow_other,max_read=131072)

I will delete it and re-add it, but I think this might be part of the problem. Perhaps me and Jim have the same issue because oVirt is actually not passing the additional mount options from the web UI to the backend to mount with said parameters?

Thoughts?

On Mon, Sep 4, 2017 at 10:51 AM, FERNANDO FREDIANI <fernando.frediani@upx.com> wrote:

I had the very same impression. It doesn't look like that it works then. So for a fully redundant where you can loose a complete host you must have at least 3 nodes then ?

Fernando


On 01/09/2017 12:53, Jim Kusznir wrote:
Huh...Ok., how do I convert the arbitrar to full replica, then?  I was misinformed when I created this setup.  I thought the arbitrator held enough metadata that it could validate or refudiate  any one replica (kinda like the parity drive for a RAID-4 array).  I was also under the impression that one replica  + Arbitrator is enough to keep the array online and functional.

--Jim

On Fri, Sep 1, 2017 at 5:22 AM, Charles Kozler <ckozleriii@gmail.com> wrote:
@ Jim - you have only two data volumes and lost quorum. Arbitrator only stores metadata, no actual files. So yes, you were running in degraded mode so some operations were hindered.

@ Sahina - Yes, this actually worked fine for me once I did that. However, the issue I am still facing, is when I go to create a new gluster storage domain (replica 3, hyperconverged) and I tell it "Host to use" and I select that host. If I fail that host, all VMs halt. I do not recall this in 3.6 or early 4.0. This to me makes it seem like this is "pinning" a node to a volume and vice versa like you could, for instance, for a singular hyperconverged to ex: export a local disk via NFS and then mount it via ovirt domain. But of course, this has its caveats. To that end, I am using gluster replica 3, when configuring it I say "host to use: " node 1, then in the connection details I give it node1:/data. I fail node1, all VMs halt. Did I miss something?

On Fri, Sep 1, 2017 at 2:13 AM, Sahina Bose <sabose@redhat.com> wrote:
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@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. 


/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@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@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@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@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@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@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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