[ovirt-users] Version of engine vs version of host

[Yaniv Kaul]

On Fri, Jun 16, 2017 at 6:27 PM, Gianluca Cecchi <gianluca.cecchi at gmail.com>
wrote:

> Hello,
> between problems solved in upcoming 4.1.3 release I see this:
>
> Lost Connection After Host Deploy when 4.1.3 Host Added to 4.1.2 Engine
> tracked by
> https://bugzilla.redhat.com/show_bug.cgi?id=1459484
>

I *think* the specific bug was discovered (and fixed) while developing
4.1.3.


>
>
> As a matter of principle I would prefer to force that an engine version
> must be greater or equal than all the hosts it is intended to manage.
> I don't find safe to allow this and probably unnecessary maintenance
> work... what do you think?
>
> For example if you go here:
> http://www.vmware.com/resources/compatibility/sim/
> interop_matrix.php#interop&1=&2=
>
> you can see that:
> - a vCenter Server 5.0U3 cannot manage an ESXi 5.1 host
> - a vCenter Server 5.1U3 cannot manage an ESXi 6.0 host
> - a vCenter Server 6.0U3 cannot manage an ESXi 6.5 host
>

We are more flexible ;-)

While I think it's a matter of taste, I think there are merits to upgrading
the hosts first. For example, assuming you have many hosts, to me it makes
sense to upgrade just one, see that things work well. Then, upgrade
another, perform live migration, etc, see that it's smooth, before
upgrading the manager, which is a bigger task sometimes (rollback is more
challenging, for example, it has a downtime requirements where as single
host maintenance is not requiring the same level of downtime, etc.).
In addition, there are host-based features (VDSM hooks) which do not
mandate a manager upgrade.


> In my opinion an administrator of the virtual infrastructure doesn't
> expect to be able to manage newer versions' hosts with older engines... and
> probably he/she doesn't feel this feature as a value added.
>

I'm on your side on this, as I believe the manager should always be the
most up-to-date, but I know others have different opinions and we'd like to
keep it that way.
Y.


> Just my thoughts.
> Cheers,
> Gianluca
>
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