[ovirt-users] oVirt DR: ansible with 4.1, only a subset of storage domain replicated

Tue Feb 6 09:32:38 UTC 2018

On Mon, Feb 5, 2018 at 7:20 PM, Maor Lipchuk <mlipchuk at redhat.com> wrote:
> Hi Luca,
>
> Thank you for your interst in the Disaster Recovery ansible solution, it is
> great to see users get familiar with it.
> Please see my comments inline
>
> Regards,
> Maor
>
> On Mon, Feb 5, 2018 at 7:54 PM, Yaniv Kaul <ykaul at redhat.com> wrote:
>>
>>
>>
>> On Feb 5, 2018 5:00 PM, "Luca 'remix_tj' Lorenzetto"
>> <lorenzetto.luca at gmail.com> wrote:
>>
>> Hello,
>>
>> i'm starting the implementation of our disaster recovery site with RHV
>> 4.1.latest for our production environment.
>>
>> Our production setup is very easy, with self hosted engine on dc
>> KVMPDCA, and virtual machines both in KVMPDCA and KVMPD dcs. All our
>> setup has an FC storage backend, which is EMC VPLEX/VMAX in KVMPDCA
>> and EMC VNX8000. Both storage arrays supports replication via their
>> own replication protocols (SRDF, MirrorView), so we'd like to delegate
>> to them the replication of data to the remote site, which is located
>> on another remote datacenter.
>>
>> In KVMPD DC we have some storage domains that contains non critical
>> VMs, which we don't want to replicate to remote site (in case of
>> failure they have a low priority and will be restored from a backup).
>> In our setup we won't replicate them, so will be not available for
>> attachment on remote site. Can be this be an issue? Do we require to
>> replicate everything?
>
>
> No, it is not required to replicate everything.
> If there are no disks on those storage domains that attached to your
> critical VMs/Templates you don't have to use them as part of yout mapping
> var file
>

Excellent.

>>
>> What about master domain? Do i require that the master storage domain
>> stays on a replicated volume or can be any of the available ones?
>
>
>
> You can choose which storage domains you want to recover.
> Basically, if a storage domain is indicated as "master" in the mapping var
> file then it should be attached first to the Data Center.
> If your secondary setup already contains a master storage domain which you
> dont care to replicate and recover, then you can configure your mapping var
> file to only attach regular storage domains, simply indicate
> "dr_master_domain: False" in the dr_import_storages for all the storage
> domains. (You can contact me on IRC if you need some guidance with it)
>

Good,

that's my case. I don't need a new master domain on remote side,
because is an already up and running setup where i want to attach
replicated storage and run the critical VMs.

>>
>>
>> I've seen that since 4.1 there's an API for updating OVF_STORE disks.
>> Do we require to invoke it with a frequency that is the compatible
>> with the replication frequency on storage side.
>
>
>
> No, you don't have to use the update OVF_STORE disk for replication.
> The OVF_STORE disk is being updated every 60 minutes (The default
> configuration value),
>

What i need is that informations about vms is replicated to the remote
site with disk.
In an older test i had the issue that disks were replicated to remote
site, but vm configuration not!
I've found disks in the "Disk"  tab of storage domain, but nothing on VM Import.

>>
>> We set at the moment
>> RPO to 1hr (even if planned RPO requires 2hrs). Does OVF_STORE gets
>> updated with the required frequency?
>
>
>
> OVF_STORE disk is being updated every 60 minutes but keep in mind that the
> OVF_STORE is being updated internally in the engine so it might not be
> synced with the RPO which you configured.
> If I understood correctly, then you are right by indicating that the data of
> the storage domain will be synced at approximatly 2 hours = RPO of 1hr +
> OVF_STORE update of 1hr
>

We require that we can recover vms with a status that is up to 2 hours
ago. In worst case, from what you say, i think we'll be able to.

[cut]
>
> Indeed,
> We also introduced several functionalities like detach of master storage
> domain , and attach of "dirty" master storage domain which are depndant on
> the failover process, so unfortunatly to support a full recovery process you
> will need oVirt 4.2 env.
>

Ok, but if i keep master storage domain on a non replicate volume, do
i require this function?

I have to admit that i require, for subscription and support
requirements, to use RHV over oVirt. I've seen 4.2 is coming also from
that side, and we'll upgrade for sure when available.

[cut]
>
>
> Please feel free to share your comments and questions, I would very
> appreciate to know your user expirience.

Sure, i'll do! And i'll bother you on irc if i need some guidance :-)

Thank you so much,

Luca

-- 
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Gottfried Wilhelm von Leibnitz, Filosofo e Matematico (1646-1716)

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Luca 'remix_tj' Lorenzetto, http://www.remixtj.net , <lorenzetto.luca at gmail.com>