Ganeti is a tool for the management of Virtualization clusters. It offers very easy management of systems with multiple virtualization servers and deployment of instances on these. It includes user-transparent setup of mirrored disks for these nodes with DRBD, running commands on all cluster noes and distributing files on the whole cluster.
Experimental support for HVM Xen is available, and support of KVM as Hypervisor, as well as libvirt for controlling the systems is in development.
It was originally developed in house at Google for internal usage on test systems, and as 1.0 released after a while under the GPL license.