libvirt users - Sep 2013 - Migrate hangs at 99%

Hello guys!

We have a lot of virtual machines and I recently tried out the migrate
feature of libvirt.

It works like a charm, even without shared storage, but when we try to
migrate a VM under a little pressure (a HTTP server gets some 1-5
requests/sec) the migration process hangs at 99%.

After we stop the stressing of the VM, the migration immediately finishes.

I'm using the following command to migrate:
virsh migrate --live --persistent --undefinesource --copy-storage-all
--verbose --desturi qemu+ssh://root@DESTINATION/system VM-NAME

Do you have any advice on this?

Üdvözlettel / Best regards
Gergely Horváth | gergely.horvath@inepex.com
http://inepex.com | IT Development and Location Based Services
http://inetrack.com | The customizable fleet tracking platform

> It works like a charm, even without shared storage, but when we try to
> migrate a VM under a little pressure (a HTTP server gets some 1-5
> requests/sec) the migration process hangs at 99%.
The maxdowntime is probably too low for the migration to complete. Try
setting it to a higher value :
virsh migrate-setmaxdowntime <domain> <seconds>

Please tell me if it worked.

Hello Anthony,
> virsh migrate-setmaxdowntime <domain> <seconds>
The migrate-setmaxdowntime operates with milliseconds, but apart from
that, we were able to migrate the VM under heavy load (8 CPUs running at
100%, load being 17-20 constantly)

We used a maximum downtime of 1000 milliseconds and it popped to the
other host right after we issued the setmaxdowntime command.

Thank you for the idea and help!

Üdvözlettel / Best regards
Gergely Horváth | gergely.horvath@inepex.com
http://inepex.com | IT Development and Location Based Services
http://inetrack.com | The customizable fleet tracking platform