Ubuntu uses KVM as the backend virtualisation technology and libvirt as its toolkit/API. Libvirt frontends for managing VMs include virt-manager GUI or virsh CLI. Alternative management options include convirt GUI or convirt2 WWW.
Installation - Installation and removal of KVM
Are you having performance issues? Why having bigger servers is not always the answer! Many of the recommendations are easy to follow and should make a significant difference in user s perception of download speeds.