[ovirt-users] upgrade hosted-engine os ( not hosts )

[Paul Groeneweg | Pazion]

Hi Yedidyah,

Thank you for the comprehensive answers.

I think I go for a complete reinstall ( read also OS upgrade tool is not
adviced on 6.6 or higher as there might be newer packages as on 7 ). No
doubting to re-use current VM or setup from scratch ( fresh host with new
hosted-engine and existing storage domein ).

You explain the steps ( 1 to 6 ), but then don't talk about storage domain
import.
Does it mean, when I reinstall the hosted-engine in the current he VM
and restore
an engine-backup ( step 5 ) I am able to start vm from Host and it is still
connected to the master storage ( so no need for storage import) ?

Best Regards,
Paul Groeneweg


Op do 30 jun. 2016 om 08:00 schreef Yedidyah Bar David <didi at redhat.com>:

> On Wed, Jun 29, 2016 at 10:07 PM, Paul Groeneweg | Pazion
> <paul at pazion.nl> wrote:
> >
> > I am looking for a way to get my hosted-engine running on el7 so I can
> > upgrade to oVirt 4.0. Currently my hosts already run el7, but my
> > hosted-engine is still el6.
> >
> > I read
> >
> https://www.ovirt.org/documentation/how-to/hosted-engine-host-OS-upgrade/
> > but this is only about the hosts.
> >
> > I read https://www.ovirt.org/documentation/how-to/hosted-engine/, but it
> > only mentions upgrade of the hosted-engine software, not the OS.
> >
> > I understood I can do a fresh hosted-engine install, and then import my
> > storage domain to the new hosted engine, but:
> >
> > - Do I need to restore my hosted engine database? ( like described here:
> >
> http://www.ovirt.org/develop/developer-guide/engine/migrate-to-hosted-engine/
> > )
>
> You might not have to, if you only care about the imported VMs from your
> storage. This will not keep other configuration, such as
> users/roles/permissions
> etc.
>
> > - Can I directly install hosted-engine 4.0 and then import the storage
> > domain? Or should I install same hosted-engine version?
>
> AFAIK 4.0 engine can import 3.6 storage domains without problem.
>
> > - Do I first need another master storage domain or can I directly import
> my
> > old master storage domain?
>
> No idea. Even if you do, you can create a small empty one and later remove
> it.
>
> > - When importing the storage domain what is the risk it fails ( I have
> > backups, but it would cost a day to restore all )
>
> No idea, but IIRC we got many successful reports and at most few failures
> for this.
>
> > - How long would import take? few minutes or hours? ( I want to keep down
> > time as low as possible ).
>
> Again no idea. Perhaps do some test?
>
> >
> > Another option would be upgrade the OS ( with redhat-upgrade-tool ) or is
> > this a path for disaster?
>
> Didn't work for us well, so we decided to not support it. If you decide to
> try,
> make sure you test carefully beforehand. From ovirt's POV:
> 1. You'll need to handle postgresql upgrade.
> 2. Right after OS upgrade, you'll still have (I think) el6 packages
> of the engine. It will hopefully be in a good-enough state for upgrade
> to 4.0, but we didn't test this.
> 3. Specifically, if upgrade fails, rollback will most likely not work,
> so you'll have to manually handle this - take a full vm backup and make
> sure you can restore it.
>
> >
> > I hope someone can tell me how I can smoothly upgrade my hosted-engine
> up to
> > el7 and run oVirt 4.
>
> We are working on a tool/wizard to help with this process. It used to work,
> but at some point it was decided that one of the actions it does is risky
> and was blocked, thus the tool is broken currently.
>
> You can invoke the tool by running: 'hosted-engine --upgrade-appliance'.
> As noted above, this is currently broken.
>
> There are several open bugs about it, e.g.:
>
> https://bugzilla.redhat.com/show_bug.cgi?id=1319457
> https://bugzilla.redhat.com/show_bug.cgi?id=1343425
> https://bugzilla.redhat.com/show_bug.cgi?id=1343593 (closed, this is
> what broke the tool)
>
> Basically, you can manually do what the tool is supposed to do:
> 1. Make sure state is clean and stable (no running/pending storage actions,
> no VMs in the middle of migration etc), all clusters are compat level 3.6,
> etc.
> 2. Move to global maintenance
> 3. backup the engine using engine-backup and keep the backup elsewhere
> 4. Reinstall engine vm with el7 and 4.0 engine (the tool will use the
> engine
> appliance, you might too but not sure how exactly).
> 5. Restore the backup and run engine-setup.
> 6. If all looks ok, leave global maintenance.
>
> If you manually keep a full backup of the engine vm before step 4,
> you might be able to restore this backup if there are problems.
> Doing this in the provided tool is currently the main blocking issue
> for it. Hopefully will be provided in 4.0.1.
>
> Best,
> --
> Didi
>
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