[Users] Is it possible to limit migration speed and number of concurrent migrations?

[Dan Kenigsberg]

On Sat, Nov 30, 2013 at 12:25:31AM +0200, Itamar Heim wrote:
> On 11/29/2013 02:08 PM, Dan Kenigsberg wrote:
> >On Fri, Nov 29, 2013 at 11:49:05AM +0100, Ernest Beinrohr wrote:
> >>I want to put some of my hvs to maintenance, but that causes a
> >>migration storm, which causes an temporary unavailability of the hv
> >>and ovirt fences it, while migrations are still running.
> >>
> >>So I have to migrate one-by-one manually and then put the hv to maintenance.
> >>
> >>Is it possible to limit migration speed and number of concurrent migrations?
> >
> >You could set max_outgoing_migrations to 1 (in each
> >/etc/vdsm/vdsm.conf), but even a single VM migrating may choke your
> >connection (depends which wins, the CPU running qemu, or your
> >bandwidth).
> >
> >Currently, your only option is to define a migration network for your
> >cluster (say, over a different nic, or over a vlan), and use tools
> >external to ovirt to throtle the bandwidth on it (virsh net-edit
> ><network name> and http://libvirt.org/formatnetwork.html#elementQoS can
> >come up handy). ovirt-3.4 should expose the ability to set QoS limits on
> >migration networks.
> >
> 
> I thought we can control both the number of concurrent migrations
> and the bandwidth per migration which defaults to 30MB/s?

You are perfectly right: I forgot about 'migration_max_bandwidth', which
vdsm sets to 32MiBps (per single migration).

Sorry for misleading the list and its archives.