Live Migrating QEMU-KVM Virtual Machines(developerblog.redhat.com)
developerblog.redhat.com
Live Migrating QEMU-KVM Virtual Machines
http://developerblog.redhat.com/2015/03/24/live-migrating-qemu-kvm-virtual-machines/
3 comments
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...
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...
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.
I suppose a hardware battery-backed write cache might still be safe for live migrations.
Users SSH sessions may lag for a second or two, but the connection won't even get dropped.