"Also, if your virtual server goes down you have lost lots of boxes rather than just one," he added.
He recommended firms to baseline test the performance of their apps to ensure that those running on a virtualised server run at the same performance levels as those on dedicated servers.
"IT should be looking to minimise the risk involved [in adopting virtualisation]," said James. "Therefore they should make one change at a time and do measurements before and after."
James also argued that companies need to take care when configuring their virtual servers' host machine, because if it is misconfigured it could overload and bring down all the apps sitting on it.
"There is one more machine to monitor in virtual environments," he added. " You need to monitor each virtual machine but also the external host machine – so there's an extra layer of complexity,"