Virtualisation is obviously a long overdue technology to reduce the number of ridiculously lightly loaded servers littering our landscape. I am sure that the software will develop and get easier and easier to install and manage but it is not clear what some of the cost may be in numerical terms. What is the typical overhead, or performance cost in virtualising a server. Clearly one option (Which I know has its down side) is to combine the functions of a number of servers onto one but how much throughput can be expected from a virtualised machine compared with a native machine? Roland Pullen »