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

[Simone Tiraboschi]

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.


>
>>    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.

>
>>    1. The original docs I read didn't mention that it's best to leave a
>>    host in maintenance mode before running the engine backup, so my plan is to
>>    install a new temporary host on a separate server, re-add the old hosts &
>>    then once everything's back up, remove the temporary host. Are there any
>>    faults in this plan?
>>    2. When it comes to deleting the old HE VM, the docs point to a
>>    paywalled guide on redhat.com...?
>>
>>  To add a bit more info to 4), I'm referring to the following...
>
> Note: If the Engine database is restored successfully, but the Engine
>> virtual machine appears to be Down and cannot be migrated to another
>> self-hosted engine host, you can enable a new Engine virtual machine and
>> remove the dead Engine virtual machine from the environment by following
>> the steps provided in https://access.redhat.com/solutions/1517683.
>>
> Source: http://www.ovirt.org/documentation/self-hosted/
> chap-Backing_up_and_Restoring_an_EL-Based_Self-Hosted_Environment/
>
>
If you are re-importing the backup in place on the initial engine VM you
don't have to.
The point is just if you are migrating to a new engine VM and so you have
to remove the entry of the previous one to let the auto-import process
trigger again.


> CentOS 7
>> oVirt 4.0.4
>> Gluster 3.8
>>
>> * Apparently a write somehow cleared fsync, despite not actually having
>> been written to disk?! No idea how that happened...
>>
>> Many thanks,
>> --
>> Doug
>>
>
> Cheers,
> --
> Doug
>
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>
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