On Thu, May 25, 2017 at 2:26 PM, Oved Ourfali <oourfali@redhat.com> wrote:


On Thu, May 25, 2017 at 12:16 PM, Michal Skrivanek <mskrivan@redhat.com> wrote:
Hi all,
I believe that introduction of bug 1413150 (Add warning to change CL to the match the installed engine version) may have an unfortunate consequence of people actually moving forward with the CL and DC without realizing the constraints on running existing VMs. The periodic nagging is likely going to make people run into the following issue even more frequently


Shall we note on cluster upgrade operation that the user should be aware of the implications?
Do we know in advance those constraints and whether that are relevant in the environment, and if it is then not issue the warning?
 
We have a cluster level override per VM which takes care of compatibility on CL update by setting the VM’s override to the original CL - that is visible in VM properties, but that’s pretty much it, it’s not very prominent at the moment and it can’t be searched on (bug 1454389). When the update cluster change is made there is a dialog informing you, and there’s also the pending config change for those running VMs…until you shut the VM down, from that time on it only has the CL override set.

But the real problem is with DC which AFAIK does not have an override capability, and currently does not have any checks for running VMs. With the above mechanism you can easily get a VM with CL override (say. 3.6) and mindlessly updated DC to 4.1…and once you stop such VM you won’t be able to start it anymore as there is a proper check for unsupported 3.6 CL VM in a newer DC (as implemented by bug 1436577 - Solve DC/Cluster upgrade of VMs with now-unsupported custom compatibility level)

I don't recall. Do we have a warning on data center level as well? Or only cluster level?

​Yes, yes we have an weekly alert for both data center and cluster which are not upgraded to latest version (level).
​
 
 

We either need to warn/block on DC upgrade, or implement some kind of a DC override (I guess this is a storage question?)

(Similar to my question above), do we have a way to identify those constraints and whether they are relevant in the environment? And if so, block upgrading of the DC level?

​We can add similar weekly alert for all VMs which cluster_level_override does not match data center version, but that's only alert. We could also prevent data center upgrade if any running VM contains lower cluster_level_override than cluster level which they belong to. But there is a question: we know that VMs should be restarted to be properly upgraded to the cluster level, but do they also need to be restarted after data center level is upgraded?​ Dan/Allon could you confirm/refute from the point of networking/storage features bound to data center level?

 

Thoughts/ideas?

Thanks,
michal
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