[ovirt-users] Restoring Hosted-Engine from a stale backup

[Doug Ingham]

Hi All, Simone,

On 24 January 2017 at 10:11, Simone Tiraboschi <stirabos at redhat.com> wrote:

>
>
> On Tue, Jan 24, 2017 at 1:49 PM, Doug Ingham <dougti at gmail.com> wrote:
>
>> Hey guys,
>>  Just giving this a bump in the hope that someone might be able to
>> advise...
>>
>> Hi all,
>>>  One of our engines has had a DB failure* & it seems there was an
>>> unnoticed problem in its backup routine, meaning the last backup I've got
>>> is a couple of weeks old.
>>> Luckily, VDSM has kept the underlying VMs running without any
>>> interruptions, so my objective is to get the HE back online & get the hosts
>>> & VMs back under its control with minimal downtime.
>>>
>>> So, my questions are the following...
>>>
>>>    1. What problems can I expect to have with VMs added/modified since
>>>    the last backup?
>>>
>>> Modified VMs will be reverted to the previous configuration; additional
> VMs should be seen as external VMs, then you could import.
>

Given VDSM kept the VMs up whilst the HE's been down, how will the running
VMs that were present before & after the backup be affected?

Many of the VMs that were present during the last backup are now on
different hosts, including the HE VM. Will that cause any issues?


>
>
>>
>>>    1. As it's only the DB that's been affected, can I skip redeploying
>>>    the Engine & jump straight to restoring the DB & rerunning engine-setup?
>>>
>>>
> Yes, if the engine VM is fine, you could just import the previous backup
> and run engine-setup again.
> Please set the global maintenance mode for hosted-engine since
> engine-backup and engine-setup are going to bring down the engine.
>

As per above, do I still only need to import the previous backup even if
the all of the VMs (including the HE VM) are now on different hosts to when
the backup was made?


And as for the future, is it going to be necessary to always keep an unused
host in the cluster to allow for emergency restores? I'm a bit concerned
that if we ever utilised all of our hosts for running VMs, then we'd be
completely stuck if the HE ever imploded again.

Cheers,
-- 
Doug
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