Re: [ovirt-users] hyperconverged question

@ Jim - here is my setup which I will test in a few (brand new cluster) and report back what I found in my tests - 3x servers direct connected via 10Gb - 2 of those 3 setup in ovirt as hosts - Hosted engine - Gluster replica 3 (no arbiter) for all volumes - 1x engine volume gluster replica 3 manually configured (not using ovirt managed gluster) - 1x datatest volume (20gb) replica 3 manually configured (not using ovirt managed gluster) - 1x nfstest domain served from some other server in my infrastructure which, at the time of my original testing, was master domain I tested this earlier and all VMs stayed online. However, ovirt cluster reported DC/cluster down, all VM's stayed up As I am now typing this, can you confirm you setup your gluster storage domain with backupvol? Also, confirm you updated hosted-engine.conf with backupvol mount option as well? On Fri, Sep 1, 2017 at 4:22 PM, Jim Kusznir <jim(a)palousetech.com&gt; wrote: > So, after reading the first document twice and the 2nd link thoroughly > once, I believe that the arbitrator volume should be sufficient and count > for replica / split brain. EG, if any one full replica is down, and the > arbitrator and the other replica is up, then it should have quorum and all > should be good. > > I think my underlying problem has to do more with config than the replica > state. That said, I did size the drive on my 3rd node planning to have an > identical copy of all data on it, so I'm still not opposed to making it a > full replica. > > Did I miss something here? > > Thanks! > > On Fri, Sep 1, 2017 at 11:59 AM, Charles Kozler <ckozleriii(a)gmail.com&gt; > wrote: > >> These can get a little confusing but this explains it best: >> https://gluster.readthedocs.io/en/latest/Administrator >> %20Guide/arbiter-volumes-and-quorum/#replica-2-and-replica-3-volumes >> >> Basically in the first paragraph they are explaining why you cant have >> HA with quorum for 2 nodes. Here is another overview doc that explains some >> more >> >> http://openmymind.net/Does-My-Replica-Set-Need-An-Arbiter/ >> >> From my understanding arbiter is good for resolving split brains. Quorum >> and arbiter are two different things though quorum is a mechanism to help >> you **avoid** split brain and the arbiter is to help gluster resolve split >> brain by voting and other internal mechanics (as outlined in link 1). How >> did you create the volume exactly - what command? It looks to me like you >> created it with 'gluster volume create replica 2 arbiter 1 {....}' per your >> earlier mention of "replica 2 arbiter 1". That being said, if you did that >> and then setup quorum in the volume configuration, this would cause your >> gluster to halt up since quorum was lost (as you saw until you recovered >> node 1) >> >> As you can see from the docs, there is still a corner case for getting >> in to split brain with replica 3, which again, is where arbiter would help >> gluster resolve it >> >> I need to amend my previous statement: I was told that arbiter volume >> does not store data, only metadata. I cannot find anything in the docs >> backing this up however it would make sense for it to be. That being said, >> in my setup, I would not include my arbiter or my third node in my ovirt VM >> cluster component. I would keep it completely separate >> >> >> On Fri, Sep 1, 2017 at 2:46 PM, Jim Kusznir <jim(a)palousetech.com&gt; wrote: >> >>> I'm now also confused as to what the point of an arbiter is / what it >>> does / why one would use it. >>> >>> On Fri, Sep 1, 2017 at 11:44 AM, Jim Kusznir <jim(a)palousetech.com&gt; >>> wrote: >>> >>>> Thanks for the help! >>>> >>>> Here's my gluster volume info for the data export/brick (I have 3: >>>> data, engine, and iso, but they're all configured the same): >>>> >>>> Volume Name: data >>>> Type: Replicate >>>> Volume ID: e670c488-ac16-4dd1-8bd3-e43b2e42cc59 >>>> Status: Started >>>> Snapshot Count: 0 >>>> Number of Bricks: 1 x (2 + 1) = 3 >>>> Transport-type: tcp >>>> Bricks: >>>> Brick1: ovirt1.nwfiber.com:/gluster/brick2/data >>>> Brick2: ovirt2.nwfiber.com:/gluster/brick2/data >>>> Brick3: ovirt3.nwfiber.com:/gluster/brick2/data (arbiter) >>>> Options Reconfigured: >>>> performance.strict-o-direct: on >>>> nfs.disable: on >>>> user.cifs: off >>>> network.ping-timeout: 30 >>>> cluster.shd-max-threads: 8 >>>> cluster.shd-wait-qlength: 10000 >>>> cluster.locking-scheme: granular >>>> cluster.data-self-heal-algorithm: full >>>> performance.low-prio-threads: 32 >>>> features.shard-block-size: 512MB >>>> features.shard: on >>>> storage.owner-gid: 36 >>>> storage.owner-uid: 36 >>>> cluster.server-quorum-type: server >>>> cluster.quorum-type: auto >>>> network.remote-dio: enable >>>> cluster.eager-lock: enable >>>> performance.stat-prefetch: off >>>> performance.io-cache: off >>>> performance.read-ahead: off >>>> performance.quick-read: off >>>> performance.readdir-ahead: on >>>> server.allow-insecure: on >>>> [root@ovirt1 ~]# >>>> >>>> >>>> all 3 of my brick nodes ARE also members of the virtualization cluster >>>> (including ovirt3). How can I convert it into a full replica instead of >>>> just an arbiter? >>>> >>>> Thanks! >>>> --Jim >>>> >>>> On Fri, Sep 1, 2017 at 9:09 AM, Charles Kozler <ckozleriii(a)gmail.com&gt; >>>> wrote: >>>> >>>>> @Kasturi - Looks good now. Cluster showed down for a moment but VM's >>>>> stayed up in their appropriate places. Thanks! >>>>> >>>>> < Anyone on this list please feel free to correct my response to Jim >>>>> if its wrong> >>>>> >>>>> @ Jim - If you can share your gluster volume info / status I can >>>>> confirm (to the best of my knowledge). From my understanding, If you setup >>>>> the volume with something like 'gluster volume set <vol> group virt' this >>>>> will configure some quorum options as well, Ex: >>>>> http://i.imgur.com/Mya4N5o.png >>>>> >>>>> While, yes, you are configured for arbiter node you're still losing >>>>> quorum by dropping from 2 -> 1. You would need 4 node with 1 being arbiter >>>>> to configure quorum which is in effect 3 writable nodes and 1 arbiter. If >>>>> one gluster node drops, you still have 2 up. Although in this case, you >>>>> probably wouldnt need arbiter at all >>>>> >>>>> If you are configured, you can drop quorum settings and just let >>>>> arbiter run since you're not using arbiter node in your VM cluster part (I >>>>> believe), just storage cluster part. When using quorum, you need > 50% of >>>>> the cluster being up at one time. Since you have 3 nodes with 1 arbiter, >>>>> you're actually losing 1/2 which == 50 which == degraded / hindered gluster >>>>> >>>>> Again, this is to the best of my knowledge based on other quorum >>>>> backed software....and this is what I understand from testing with gluster >>>>> and ovirt thus far >>>>> >>>>> On Fri, Sep 1, 2017 at 11:53 AM, Jim Kusznir <jim(a)palousetech.com&gt; >>>>> 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(a)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(a)redhat.com&gt; >>>>>>> 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(a)kafit.se&gt; 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.readthed >>>>>>>>> ocs.io/en/latest/Administrator%20Guide/arbiter-volumes-and-q >>>>>>>>> uorum/ >>>>>>>>> >>>>>>>>> /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(a)gmail.com&gt; 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(a)gmail.com&gt; 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(a)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(a)gmail.com&gt; 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(a)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(a)gmail.com&gt; 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? >>>>>>>>> >>>>>>>>> _______________________________________________ >>>>>>>>> Users mailing list >>>>>>>>> Users(a)ovirt.org >>>>>>>>> http://lists.ovirt.org/mailman/listinfo/users >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> _______________________________________________ >>>>>>>>> Users mailing list >>>>>>>>> Users(a)ovirt.org >>>>>>>>> http://lists.ovirt.org/mailman/listinfo/users >>>>>>>>> >>>>>>>>> >>>>>>>>> _______________________________________________ >>>>>>>>> Users mailing listUsers@ovirt.orghttp://lists.ovirt.org/mailman/listinfo/users >>>>>>>>> >>>>>>>>> >>>>>>>>> _______________________________________________ >>>>>>>>> Users mailing list >>>>>>>>> Users(a)ovirt.org >>>>>>>>> http://lists.ovirt.org/mailman/listinfo/users >>>>>>>>> >>>>>>>>> >>>>>>>> >>>>>>> >>>>>>> _______________________________________________ >>>>>>> Users mailing list >>>>>>> Users(a)ovirt.org >>>>>>> http://lists.ovirt.org/mailman/listinfo/users >>>>>>> >>>>>>> >>>>>> >>>>> >>>> >>> >> >