
Live Migrating QEMU-KVM Virtual Machines - Tsiolkovsky
http://developerblog.redhat.com/2015/03/24/live-migrating-qemu-kvm-virtual-machines/
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X-Istence
I've used live migration with KVM within OpenStack and it is really damn
awesome to be able to migrate all VM's from a host that needs to be downed for
maintenance without causing any downtime.

Users SSH sessions may lag for a second or two, but the connection won't even
get dropped.

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anemic
I tried this a while ago with libbirt-kvm and the most awesome thing was that
I could live migrate VMs from AMD to Intel and vice versa. None of the other
solutions, like vmware or xen do that, afaik.

On the not so good side is that disk cache needs to be disabled for live
migration to work at all. This reduces the iops of the vm by 50-60%.

So you either get high performance or high uptime...

~~~
chousuke
I think you'd generally want the host not to do write caching anyway unless
you can afford to corrupt VM disks in case of host power failure.

I suppose a hardware battery-backed write cache might still be safe for live
migrations.

------
RRRA
Anyone has a solution for Live backups?

Say something that migrates the machine and initiate a shutdown as soon as it
hits the other backup server?

~~~
amitshah
oVirt can do this. Essentially, such policies belong to management
applications, and oVirt or OpenStack are the places where you should look.

