Hi,

you are mixing 2 unrelated versioning parts:

1. Supported cluster levels
    - oVirt Engine 4.5 supports cluster level 4.2 - 4.7
         https://github.com/oVirt/ovirt-engine/blob/master/backend/manager/modules/compat/src/main/java/org/ovirt/engine/core/compat/Version.java#L22
    - This means that both EL7 based (4.2 and 4.3) and EL8 based (4.4-4.7) hosts can be successfully managed by oVirtEngine 4.5

2. OS requirements of oVirt Engine 4.5
    - oVirt Engine 4.5 is supported only on EL 8.6+ and CS8 stream
    - This means that:
        - for standalone engine you need to have a machine with EL8.6 or CS8
        - for hosted engine you need to have a cluster with EL8.6 or CS8 hosts, where hosted engine VM based on E8.6 or CS8 can run

So specifically for your use case you need:

1. Standalone engine 4.5 running on EL8.6 or CS8, which can manage 4.2 hosts in 4.2 cluster
2. Hosted engine 4.5 running on cluster of EL8.6 or CS8 hosts with additional (different) 4.2 cluster, where your 4.2 hosts reside

Regards,
Martin


On Mon, Aug 29, 2022 at 2:43 PM Jirka Simon <jirka@vesim.cz> wrote:
Hi Andrei,

ovirt 4.4+ has to run with centos/ rhel 8, I would not recommend mix
versions of ovirt node version within one cluster. (there couldbe / will
be a problem with vdsm version on each node)

And yes cluster compatibility version number doesn't match  ovirt version.

I would recommend to try to remove the oldest node from the cluster (if
upu have some spare nodes) and try to reinstall it to centos 8 or 9 with
standalone engine for test if it works or not.

Jirka

On 8/29/22 14:26, Andrei Verovski wrote:
> Hi,
>
> My oldest nodes are version 4.2 on CentOS 7.6.
> What is the latest cluster compatibility level they support?
> Looks like oVirt Engine version and cluster compatibility level do not match number to number, e.g. my oVirt engine 4.4.10 seems can set cluster compatibility level up to 4.6.
>
> Someone from Red Hat, please clarify.
> Thanks in advance.
>
>
>> On 29 Aug 2022, at 15:09, Jirka Simon <jirka@vesim.cz> wrote:
>>
>> Hi Andrei,
>>
>> as I know,  you need to have to have your cluster with at least 4.3 version to migrate to 4.5. I was facing the same  problem with (not so) old hardware. and i started to do step by step migration.
>>
>> it means i created new cluster with fresh configuration with ovirt 4.5  and cluster compatibility version 4.7 next to old one with 4.4.   Iit is a good opportunity to prepare whole cluster configuration in ansible for me :D
>>
>> Then I migrate VMs one by one from old cluster to the new one. When is one node free on old cluster I reinstall it and add to new cluster.
>>
>> Maybe it is not the fastest solution, but i can arrange maintenance for each VM.
>>
>> Jirka
>>
>> On 8/29/22 10:13, Andrei Verovski wrote:
>>> Hi,
>>>
>>> I have cluster compatibility version 4.2, due to some old nodes.
>>>  From what I remember in oVirt 4.5 release notes (correct please, may be wrong here), oVirt engine 4.5 requires cluster compatibility version >= 4.3.
>>> Please clarify. Thanks.
>>>
>>>
>>>>> On 28. 8. 2022, at 18:52, Andrei Verovski <andreil1@starlett.lv> wrote:
>>>>>
>>>>> Hi,
>>>>>
>>>>> I have engine version 4.4.10.7-1.el8, is it possible to set up new node host on CentOS Stream 9, or I need to upgrade engine to version 4.5 first (which is not right now possible because of some quite old nodes) ?
>>>> yes, you generally need the latest version
>>>> You can keep your old nodes old, 4.2 based nodes are still working with 4.5
>>>>
>>>>> Thanks
>>>>> Andrei
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--
Martin Perina
Manager, Software Engineering
Red Hat Czech s.r.o.