[ovirt-users] Failed migration - Migration is stuck

[Michal Skrivanek]

> On 21 Apr 2016, at 13:31, Ollie Armstrong <ollie at fubra.com> wrote:
> 
> I'm having some issues with a couple of VMs in my cluster that cannot
> be live migrated between hosts.  It appears to be the issue that is
> referenced by https://access.redhat.com/solutions/870113 and
> https://access.redhat.com/solutions/1159723.
> 
> I currently have a dedicated 1Gbps network for migrations and have
> modified some of my vdsm settings so that my vdsm.conf looks like
> this:
> 
> [vars]
> ssl = true
> migration_timeout = 600
> migration_max_bandwidth = 100
> max_outgoing_migrations = 3

you should lower this, otherwise it won’t fit (1 migration at 100MBps would eat your whole link already). So use 1

> migration_downtime = 1000

it’s not really 1000. There’s a UI for that in Edit VM, so you shouldn’t set it here at all
and if you do, the algorithm behind it is not-so-great in <=3.6.5. 
Use migration_downtime_steps=3 or 5 or something lower to mitigate that wrong algorithm behavior

if you need to overcome a longer peak period of activity, also change migration_progress_timeout to something more than 150s

Thanks,
michal

> 
> [addresses]
> management_port = 54321
> 
> The issue was happening before the configuration changes too.
> 
> The relevant lines from my vdsm.log from the host that the VM is being
> migrated from: http://ix.io/xeT
> 
> Has anyone been able to resolve this or come up with a workaround for
> this problem?  I understand that it is because the migration cannot
> occur as fast as the changes in the VM are happening so this could be
> difficult to get working.  Some downtime is acceptable for these VMs,
> so if there are further config changes that can be made which allow
> for more downtime then I would consider that a solution.
> 
> Ollie
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