The Qemu-KVM 0.12 release includes a very interesting new feature based on patches provides back in november 2009 by IBM.
This KVM version has a new feature called block migration which allows you to do block migration during the live migration of a VM.
The concept is pretty similar to RAM migration. First the full disk is being copied , then the dirty blocks are being copie. Having this feature means that you can do live migration without having shared storage available.
Obviously performance will be lower and you might end up with a bigger hickup at the final phase of the migration than in a regular live migration.
On the Windows side of KVM the biggest news is that the Balloon Drive code has been GPL repository of the KVM windows guest driver. Up till now Linux was the only operating system that supported ballooning … now work is under way to have windows supported too. The block drivers for windows XP have also been updated in that repository. The iso with the new drivers can be found here
In other KVM news Chris Wright, a Principal Engineer at RedHat announced to the KVM Mailing list last month that the annual KVM forum is planned next to the Linux Foundation’s LinuxCon 2010 which will be held in Boston this August. The KVM summit is scheduled for August 9th and 10th
You can use DRBD to this with kvm/xen