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@redhat.com> wrote:


On Feb 5, 2018 5:00 PM, "Luca 'remix_tj' Lorenzetto" <lorenzetto.luca@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
 
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)
 

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), 
 
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
 

I've seen a recent presentation by Maor Lipchuk that is showing the
"automagic" ansible role for disaster recovery:

https://www.slideshare.net/maorlipchuk/ovirt-dr-site-tosite-using-ansible

It's also related with some youtube presentations demonstrating a real
DR plan execution.

But what i've seen is that Maor is explicitly talking about 4.2
release. Does that role works only with >4.2 releases or can be used
also on earlier (4.1) versions?

Releases before 4.2 do not store complete information on the OVF store to perform such comprehensive failover. I warmly suggest 4.2!
Y.

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.



I've tested a manual flow of replication + recovery through Import SD
followed by Import VM and worked like a charm. Using a prebuilt
ansible role will reduce my effort on creating a new automation for
doing this.

Anyone has experiences like mine?

Thank you for the help you may provide, i'd like to contribute back to
you with all my findings and with an usable tool (also integrated with
storage arrays if possible).

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

Luca

(Sorry for duplicate email, ctrl-enter happened before mail completion)


--
"E' assurdo impiegare gli uomini di intelligenza eccellente per fare
calcoli che potrebbero essere affidati a chiunque se si usassero delle
macchine"
Gottfried Wilhelm von Leibnitz, Filosofo e Matematico (1646-1716)

"Internet è la più grande biblioteca del mondo.
Ma il problema è che i libri sono tutti sparsi sul pavimento"
John Allen Paulos, Matematico (1945-vivente)

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