[ovirt-users] Network & local disk on same host, live storage migration

[Alexander Wels]

On Thursday, April 07, 2016 11:28:18 AM Matthew Bohnsack wrote:
> Thanks for your responses.
> 
> Is gaining the ability to have local and shared storage domains in the same
> datacenter (and therefore host) on the roadmap? It's most certainly
> functionality we require in our virtual environment.
> 

Honestly I don't know, I don't see it happening any time soon. I haven't heard 
anyone wanting it. AFAIK most of the effort right now is focused on getting 
hyper convergence with gluster working correctly and getting all the edge 
cases to behave.

IIRC you can't mix and match local and shared due to only shared having the 
ability to live migrate while you can't do that with local storage. If it is 
something you require feel free to open an RFE in bugzilla.

> On Thu, Apr 7, 2016 at 8:44 AM, Alexander Wels <awels at redhat.com> wrote:
> > On Thursday, April 07, 2016 07:47:59 AM Matthew Bohnsack wrote:
> > > Hello.
> > > 
> > > I've been doing some experimentation with oVirt 3.6 and CentOS 7.2
> > > hosts,
> > > and I have a few high level questions, related to what I've seen in my
> > > testing:
> > > 
> > > 1/ It seems that for a given host, it's impossible to have both a local
> > > storage domain and a shared storage domain such as NFS.  Is this
> > > correct?
> > > If so, is adding this capability on the roadmap somewhere?  I would
> > 
> > really
> > 
> > > like to have the ability for a single host to simultaneously support
> > > both
> > > local and network disks.
> > 
> > Storage is defined on a data center level, not on a host level, so you are
> > correct you cannot have local storage and shared storage in the same data
> > center.
> > 
> > > 2/ Does oVirt support any sort of live storage migration functionality?
> > 
> > Yes, if you go to the disks main tab, you can select the disk you want to
> > migrate and click 'move'. This will give you a dialog that allows you to
> > select the target storage domain and profile.
> > 
> > >   2.A/ For example, say I have one host (host#1) with two separate NFS
> > > 
> > > storage domains (NFS#1 and NFS#2).  In this case,  can a VM on host#1
> > > associated with NFS#1 be live migrated to NFS#2 storage?  Or can this
> > 
> > sort
> > 
> > > of storage movement only be accomplished by a shutdown of the VM and an
> > > export/import/restart workflow?
> > > 
> > >   2.B/ Is the scenario described in 2.A possible across two different
> > 
> > hosts
> > 
> > > that share both NFS storage domains?  That is, can a VM guest on
> > > host#1/NFS#1 be live migrated to host#2/NFS#2?
> > 
> > See above answer, you can live migrate between storage domains, and since
> > storage domains are at a data center level if both hosts are in the same
> > data
> > center, and both storage domains are in the same data center, you can live
> > migrate the storage as well as the VMs. It will be 2 separate operations
> > though.
> > 
> > > 3/ Let's says that you setup a host (host#1) with a shared storage
> > > domain
> > > (NFS#1) and a second host (host#2) with a local storage domain
> > > (local#2).
> > > If you wanted to move a VM from host#1/NFS#1 to host#2/local#2, how
> > > would
> > > you most easily accomplish this?  All I could come up with is: Add NFS
> > > export domain to host#1, turn VM on host#1 off, export VM, add NFS
> > > import
> > > domain to host#2, import VM, on host#2 onto local#2, turn VM on on
> > 
> > host#2?
> > 
> > 
> > Since these hosts cannot be in the same data center (cannot mix shared and
> > local storage) that is the only option I know of for this particular
> > scenario.
> > 
> > > Thanks for your help,
> > > 
> > > -Matthew