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

[Eduardo Mayoral]

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