[ovirt-devel] hosted-engine setup/migration features for 3.6

Bob Doolittle bob at doolittle.us.com
Wed Dec 3 12:53:24 UTC 2014

Resending - inadvertently dropped CCs.

On Wed, Dec 3, 2014 at 7:50 AM, Bob Doolittle <bob at doolittle.us.com> wrote:

> Another issue with that page is that it assumes a remote database. I am
> not sure what percentage of cases have remote databases but clearly many
> (most?) do not, since that's not default behavior. So that page definitely
> needs attention. See:
> https://bugzilla.redhat.com/show_bug.cgi?id=1099995
> https://bugzilla.redhat.com/show_bug.cgi?id=1099998
> Some of us have wanted to disable global maintenance upon bootup by adding
> a systemd service on Fedora 20 (since you must enable global maintenance to
> shut it down cleanly), and have found it impossible to create the necessary
> systemd dependencies. It seems that (at least with 3.4) hosted-engine
> --set-maintenance --mode=none will return an error for several seconds
> after all other services have started and it's not clear what can be waited
> upon in order to issue the command with assurance it will complete
> successfully. This isn't strictly a setup/migration issue but it is an
> issue with setting up a desired configuration with hosted-engine. The way
> to reproduce this is simply to wait until gdm-greeter displays the login
> prompt, ssh into the system and execute hosted-engine --set-maintenance
> --mode=none and observe the error. Or create a systemd service that depends
> upon (waits for) the latest-possible service, try executing the command
> there, and observe the error. Ideally there would be some external
> observable event which a systemd service could depend upon, when
> hosted-engine is ready to do its thing.
> Regards,
>     Bob
> On Wed, Dec 3, 2014 at 2:59 AM, Yedidyah Bar David <didi at redhat.com>
> wrote:
>> Hi all,
>> We already have quite a lot of open ovirt-hosted-engine-setup bugs for
>> 3.6 [1].
>> Yesterday I tried helping someone on irc who planned to migrate to
>> hosted-engine
>> manually, and without knowing (so it seems) that such a feature exists.
>> He had
>> an engine set up on a physical host, prepared a VM for it, and asked
>> about migrating
>> the engine to the VM. In principle this works, but the final result will
>> be a
>> hosted-engine, where the engine manages a VM the runs itself, without
>> knowing it,
>> and without HA.
>> The current recommended migration flow is described in [2]. This page is
>> perhaps
>> a bit outdated, perhaps missing some details etc., but principally works.
>> The main
>> issue with it, AFAICT after discussing this a bit with few people, is
>> that it
>> requires a new clean host.
>> I'd like to hear what people here think about such and similar flows.
>> If you already had an engine and migrated to hosted-engine, what was
>> good, what
>> was bad, what would you like to change?
>> If you plan such a migration, what do you find missing currently?
>> [1] http://red.ht/1vle8Vv
>> [2] http://www.ovirt.org/Migrate_to_Hosted_Engine
>> Best,
>> --
>> Didi
>> _______________________________________________
>> Devel mailing list
>> Devel at ovirt.org
>> http://lists.ovirt.org/mailman/listinfo/devel
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