[ovirt-users] Question on Datacenters / clusters / data domains

[Shani Leviim]

Hi Eduardo,
Welcome aboard!

First, you may find some relevant information in here: http://www.ovirt.org/
documentation/admin-guide/administration-guide/ .

Regarding your questions:
* A data domain in an oVirt Data Center must be available to every Host on
the Data Center: Am I right?
Yes, you're right.

* Can I manually migrate VMs between Datacenters?
VM migration can't be performed between data canters, so you can't use the
'migrate VM' function.
In order to "migrate" your VM between different data canters, you can use
'export' and 'import' functions and an 'export domain':
By creating an export domain for one of your DC's (each DC can have up to
one export domain), and exporting your VM to that storage domain,
you can then detach the export domain from that DC and attach it to the
other DC, and by importing there your VM you'll finish the transaction.

Another option is to detach the VM's storage domain from one DC and attach
it the second one.
That way you'll move the whole storage domain between your DCs.

If you have any further questions, don't hesitate to ask :)


*Regards,*

*Shani Leviim*

On Thu, Aug 24, 2017 at 2:51 PM, Eduardo Mayoral <emayoral at arsys.es> wrote:

> Hi,
>
>     First of all, sorry for the naive question, but I have not been able
> to find good guidance on the docs.
>
>     I come from the VMWare environment, now I am starting to migrate
> some workload from VMWare to oVirt (v4.1.4 , CentOS 7.3 hosts).
>
>     In VMWare I am used to have one datacenter, several host clusters,
> and a bunch of iSCSI Datastores, but we do not map every iSCSI
> LUN/datastore to every host. Actually we used to do that, but we hit
> limits on the number of iSCSI paths with our infrastructure.
>
>     Rather than that, we have groups of LUNs/Datastores mapped to the
> ESXi hosts which form a given VMware cluster. Then we have a couple of
> datastores mapped to every ESXi in the vmware datacenter, and we use
> those to store the ISO images and as storage that we use when we need to
> migrate VMs between clusters for some reason.
>
>     Given the role of the Master data domain and the SPM in oVIrt it is
> my understanding that I cannot replicate this kind of setup in oVirt: a
> data domain in an oVirt Data Center must be available to every Host on
> the Data Center: Am I right?
>
>     So, our current setup is still small, but I am concerned that as it
> grows, if I stay with one Datacenter, several clusters and a group of
> data domains mapped to every host I may run again into problems with the
> number of iSCSI paths (the limit in VMWare was around 1024), it is easy
> to reach that limit as it is (number of hosts) * (number of LUNs) *
> (number of paths/LUN).
>
>     If I split my setup in several datacenters controlled by a single
> oVirt-engine in order to keep the number of iSCSI paths reasonable. Can
> I manually migrate VMs between Datacenters? I assume that in order to do
> that, those datacenters will need to share some data domain , Can this
> be done? Maybe with NFS?
>
>     Thanks for your help!
>
> --
> Eduardo Mayoral Jimeno (emayoral at arsys.es)
> Administrador de sistemas. Departamento de Plataformas. Arsys internet.
> +34 941 620 145 ext. 5153
>
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> Users mailing list
> Users at ovirt.org
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>
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