Virtualisation enables enterprises to consolidate kit onto fewer systems, thereby saving capital costs on hardware and software licences. This is obviously an attractive proposition, especially given the worsening economic climate.

However, one problem not yet fully addressed is how firms patch offline virtual operating system images, also known as virtual machines (VMs), together with any installed applications. According to most vendors, the ratio of offline to online images is high. It is easy to imagine a situation where a virtual web server fails over to an offline VM. Such a VM will have to be patched and firms will normally run tests to certify that all is well.

Options to allow VMs to be patched offline increased last week with the launch of a new tool by security vendor McAfee. VMware also offers software that allows offline patching, while Microsoft is working on a similar solution.

But while these developments are welcome, there is still a need for solutions that allow VMs to be patched offline at both an operation system level and application level.

The proportion of firms currently using desktop and server virtualisation is only about five per cent and 20 per cent respectively, but improvements in VM security should help to increase uptake. A tool that patches VMs offline at an OS and application level would be a surefire money-spinner.