[ovirt-devel] upgrade of CL and DC vs running VMs

[Martin Perina]

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

>
>
> On Thu, May 25, 2017 at 12:16 PM, Michal Skrivanek <mskrivan at 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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>
>
>
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