[ovirt-users] Workflow after restoring engine from backup

[Yedidyah Bar David]

On Mon, Mar 19, 2018 at 11:03 AM, Sven Achtelik <Sven.Achtelik at eps.aero> wrote:
> Hi Didi,
>
> my backups where taken with the end. Backup utility. I have 3 Data centers,
> two of them with just one host and the third one with 3 hosts running the
> engine.  The backup three days old, was taken on engine version 4.1 (4.1.7)
> and the restored engine is running on 4.1.9.

Since the bug I mentioned was fixed in 4.1.3, you should be covered.

> I have three HA VMs that would
> be affected. All others are just normal vms. Sounds like it would be the
> safest to shut down the HA vm S to make sure that nothing happens ?

If you can have downtime, I agree it sounds safer to shutdown the VMs.

> Or can I
> disable the HA action in the DB for now ?

No need to. If you restored with 4.1.9 engine-backup, it should have done
this for you. If you still have the restore log, you can verify this by
checking it. It should contain 'Resetting HA VM status', and then the result
of the sql that it ran.

Best regards,

>
> Thank you,
>
> Sven
>
>
>
> Von meinem Samsung Galaxy Smartphone gesendet.
>
>
> -------- Ursprüngliche Nachricht --------
> Von: Yedidyah Bar David <didi at redhat.com>
> Datum: 19.03.18 07:33 (GMT+01:00)
> An: Sven Achtelik <Sven.Achtelik at eps.aero>
> Cc: users at ovirt.org
> Betreff: Re: [ovirt-users] Workflow after restoring engine from backup
>
> On Sun, Mar 18, 2018 at 11:45 PM, Sven Achtelik <Sven.Achtelik at eps.aero>
> wrote:
>> Hi All,
>>
>>
>>
>> I had issue with the storage that hosted my engine vm. The disk got
>> corrupted and I needed to restore the engine from a backup.
>
> How did you backup, and how did you restore?
>
> Which version was used for each?
>
>> That worked as
>> expected, I just didn’t start the engine yet.
>
> OK.
>
>> I know that after the backup
>> was taken some machines where migrated around before the engine disks
>> failed.
>
> Are these machines HA?
>
>> My question is what will happen once I start the engine service
>> which has the restored backup on it ? Will it query the hosts for the
>> running VMs
>
> It will, but HA machines are handled differently.
>
> See also:
>
> https://bugzilla.redhat.com/show_bug.cgi?id=1441322
> https://bugzilla.redhat.com/show_bug.cgi?id=1446055
>
>> or will it assume that the VMs are still on the hosts as they
>> resided at the point of backup ?
>
> It does, initially, but then updates status according to what it
> gets from hosts.
>
> But polling the hosts takes time, especially if you have many, and
> HA policy might require faster handling. So if it polls first a
> host that had a machine on it during backup, and sees that it's
> gone, and didn't yet poll the new host, HA handling starts immediately,
> which eventually might lead to starting the VM on another host.
>
> To prevent that, the fixes to above bugs make the restore process
> mark HA VMs that do not have leases on the storage as "dead".
>
>> Would I need to change the DB manual to let
>> the engine know where VMs are up at this point ?
>
> You might need to, if you have HA VMs and a too-old version of restore.
>
>> What will happen to HA VMs
>> ? I feel that it might try to start them a second time.  My biggest issue
>> is
>> that I can’t get a service Windows to shutdown all VMs and then lat them
>> restart by the engine.
>>
>>
>>
>> Is there a known workflow for that ?
>
> I am not aware of a tested procedure for handling above if you have
> a too-old version, but you can check the patches linked from above bugs
> and manually run the SQL command(s) they include. They are essentially
> comment 4 of the first bug.
>
> Good luck and best regards,
> --
> Didi



-- 
Didi