I would go this way:
1. Backup
2. Reinstall the host (as you migrate from 4.3. to 4.4 we need EL8)
3. use command provided in previous e-mail (hosted-engine ...). to deploy to the iSCSI. Ensure the old HE VM is offline and all hosts see the iSCSI becore the restore.
4. If the deployment is OK and the new engine sees the hosts -> storage migrate the VMs from the Gluster to iSCSI

Another approach is to move the VMs first and last -> restore the HE on the iSCSI storage.

Best Regards,
Strahil Nikolov

On Wed, Mar 16, 2022 at 17:24, Yedidyah Bar David
<didi@redhat.com> wrote:
On Wed, Mar 16, 2022 at 4:45 PM Demeter Tibor <tdemeter@itsmart.hu> wrote:
>
> Dear Didi,
> Thank you for your reply.
>
> My glusterfs uses the host's internal disks. I have 4 hosts, but the glusterfs use only 3.  It is a centos7 based system.
>
> As I think, I have to elminate the glusterfs first, because I can't upgrade the hosts until the engine running on there. That's why I think the engine will access  to them after the reinstall.

Sorry, I do not think I understand your reasoning/plan. Please clarify.

> Is it fine?

If the question is:

"I have a HC hosted-engine+gluster on 3 hosts + another host. I want
to move the hosted-engine (on one of the hosts? not clear) to external
iscsi storage. Will the new engine be able to access the gluster
storage on the existing hosts?"

Then, sadly, I don't know. I *think* it will work - that gluster does
not need the engine to function - but never tried this.

> What pitfalls can I except in this case?

Many, if you ask me - mainly, because it's a flow probably hardly
anyone ever tried, and it definitely goes out of the set of
assumptions built into the basic design. I strongly suggest to test
first on a test env (can be on nested-kvm VMs, no need for physical
hosts) and to have good backups. But in theory, I can't think of any
concrete point.

Best regards,


>
> Thanks in advance,
> Tibor
>
>
> ________________________________
> Feladó: Yedidyah <didi@redhat.com>
> Címzett: Demeter <tdemeter@itsmart.hu>
> Másolat: users <users@ovirt.org>
> Dátum: 2022. március 16., szerda 15:08 CET
> Tantárgy: Re: [ovirt-users] Replace storage behind ovirt engine
>
> On Wed, Mar 16, 2022 at 1:39 PM Demeter Tibor <tdemeter@itsmart.hu> wrote:
> >
> > Dear Users,
> >
> > I have to upgrade our hyperconverged ovirt system from 4.3 to 4.4, but meanwhile I would like to change the storage backend under the engine. At this moment it is a gluster based clustered fs, but I don't really like it.... I would like to change to a hardver based iscsi storage.
> > I just wondering, when I do the engine reinstall, I will install it to an other storage.
> > Is it possible somehow?
>
> The "canonical" way is:
> 1. On current engine machine: engine-backup --file=f1
> 2. (Re)Install a new host (with 4.4?), copy there f1, and:
> hosted-engine --deploy --restore-from-file=f1
>
> This only handles your engine VM, not others. The new engine (with its
> hosted_storage on the new iscsi storage) will need access to the
> existing gluster storage holding the other VMs, if you plan to somehow
> import/migrate/whatever them. If unsure how to continue, perhaps
> clarify your plan with more details.
>
> Good luck,
> --
> Didi
>


--
Didi
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