Dear All,
I wanted to share my experience upgrading from 4.2.8 to 4.3.1. While previous upgrades from 4.1 to 4.2 etc. went rather smooth, this one was a different experience. After first trying a test upgrade on a 3 node setup, which went fine. i headed to upgrade the 9 node production platform, unaware of the backward compatibility issues between gluster 3.12.15 -> 5.3. After upgrading 2 nodes, the HA engine stopped and wouldn't start. Vdsm wasn't able to mount the engine storage domain, since /dom_md/metadata was missing or couldn't be accessed. Restoring this file by getting a good copy of the underlying bricks, removing the file from the underlying bricks where the file was 0 bytes and mark with the stickybit, and the corresponding gfid's. Removing the file from the mount point, and copying back the file on the mount point. Manually mounting the engine domain, and manually creating the corresponding symbolic links in /rhev/data-center and /var/run/vdsm/storage and fixing the ownership back to vdsm.kvm (which was root.root), i was able to start the HA engine again. Since the engine was up again, and things seemed rather unstable i decided to continue the upgrade on the other nodes suspecting an incompatibility in gluster versions, i thought would be best to have them all on the same version rather soonish. However things went from bad to worse, the engine stopped again, and all vm’s stopped working as well. So on a machine outside the setup and restored a backup of the engine taken from version 4.2.8 just before the upgrade. With this engine I was at least able to start some vm’s again, and finalize the upgrade. Once the upgraded, things didn’t stabilize and also lose 2 vm’s during the process due to image corruption. After figuring out gluster 5.3 had quite some issues I was as lucky to see gluster 5.5 was about to be released, on the moment the RPM’s were available I’ve installed those. This helped a lot in terms of stability, for which I’m very grateful! However the performance is unfortunate terrible, it’s about 15% of what the performance was running gluster 3.12.15. It’s strange since a simple dd shows ok performance, but our actual workload doesn’t. While I would expect the performance to be better, due to all improvements made since gluster version 3.12. Does anybody share the same experience?
I really hope gluster 6 will soon be tested with ovirt and released, and things start to perform and stabilize again..like the good old days. Of course when I can do anything, I’m happy to help.
I think the following short list of issues we have after the migration;
Gluster 5.5;
- Poor performance for our workload (mostly write dependent)
- VM’s randomly pause on unknown storage errors, which are “stale file’s”. corresponding log; Lookup on shard 797 failed. Base file gfid = 8a27b91a-ff02-42dc-bd4c-caa019424de8 [Stale file handle]
- Some files are listed twice in a directory (probably related the stale file issue?)
Example;
ls -la /rhev/data-center/59cd53a9-0003-02d7-00eb-0000000001e3/313f5d25-76af-4ecd-9a20-82a2fe815a3c/images/4add6751-3731-4bbd-ae94-aaeed12ea450/
total 3081
drwxr-x---. 2 vdsm kvm 4096 Mar 18 11:34 .
drwxr-xr-x. 13 vdsm kvm 4096 Mar 19 09:42 ..
-rw-rw----. 1 vdsm kvm 1048576 Mar 28 12:55 1a7cf259-6b29-421d-9688-b25dfaafb13c
-rw-rw----. 1 vdsm kvm 1048576 Mar 28 12:55 1a7cf259-6b29-421d-9688-b25dfaafb13c
-rw-rw----. 1 vdsm kvm 1048576 Jan 27 2018 1a7cf259-6b29-421d-9688-b25dfaafb13c.lease
-rw-r--r--. 1 vdsm kvm 290 Jan 27 2018 1a7cf259-6b29-421d-9688-b25dfaafb13c.meta
-rw-r--r--. 1 vdsm kvm 290 Jan 27 2018 1a7cf259-6b29-421d-9688-b25dfaafb13c.meta
- brick processes sometimes starts multiple times. Sometimes I’ve 5 brick processes for a single volume. Killing all glusterfsd’s for the volume on the machine and running gluster v start <vol> force usually just starts one after the event, from then on things look all right.
Ovirt 4.3.2.1-1.el7
- All vms images ownership are changed to root.root after the vm is shutdown, probably related to; https://bugzilla.redhat.com/show_bug.cgi?id=1666795 but not only scoped to the HA engine. I’m still in compatibility mode 4.2 for the cluster and for the vm’s, but upgraded to version ovirt 4.3.2
- The network provider is set to ovn, which is fine..actually cool, only the “ovs-vswitchd” is a CPU hog, and utilizes 100%
- It seems on all nodes vdsm tries to get the the stats for the HA engine, which is filling the logs with (not sure if this is new);
[api.virt] FINISH getStats return={'status': {'message': "Virtual machine does not exist: {'vmId': u'20d69acd-edfd-4aeb-a2ae-49e9c121b7e9'}", 'code': 1}} from=::1,59290, vmId=20d69acd-edfd-4aeb-a2ae-49e9c121b7e9 (api:54)
- It seems the package os_brick [root] managedvolume not supported: Managed Volume Not Supported. Missing package os-brick.: ('Cannot import os_brick',) (caps:149) which fills the vdsm.log, but for this I also saw another message, so I suspect this will already be resolved shortly
- The machine I used to run the backup HA engine, doesn’t want to get removed from the hosted-engine –vm-status, not even after running; hosted-engine --clean-metadata --host-id=10 --force-clean or hosted-engine --clean-metadata --force-clean from the machine itself.
Think that's about it.
Don’t get me wrong, I don’t want to rant, I just wanted to share my experience and see where things can made better.
Best Olaf
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