Roger Howorth

Intel and analyst firm Gartner say virtual server technology will be increasingly important, and vendors are now promoting virtual server systems. But unlike some other "virtual" technologies, the benefits here are very real. Virtual server technologies enable a single server to run several operating systems concurrently, and Intel is working to build this capability into all its desktop and server chips.

It turns out that the benefits fall into two categories.

First, there are operational benefits, besides the promise of much higher CPU utilisation. Server virtualisation is like disk imaging for servers. With virtualisation, servers can be configured and tested on offline systems, and then migrated to production hardware when the time is right.

Typically, this migration is almost as simple as copying a file from the prototyping system to the production one. These files are analogous to disk partitions, so one file would normally contain the operating system and application.

Currently, the biggest difficulty is accommodating such huge files in a Windows or Linux file system. This is because disk partitions are often 4GB or more in size, while Windows NTFS and standard Linux file systems such as EXT2 and ReiserFS cannot work with files that are larger than 2GB. There are ways to work around these difficulties, either by using a specialised file system that can handle the larger files, or by splitting files that are larger than 2GB into several smaller ones.

One of the most stunning capabilities of the new technology is that such migrations could soon be carried out without taking the virtual server offline.

Imagine, an organisation such as the BBC, which already transmits all its scheduled TV and radio programming digitally from its servers in London, could move the entire operation to its studios in Birmingham without a glitch in the broadcasting.

There are also strategic advantages to a virtual approach. With hardware-independent servers, firms should become less reliant on a particular hardware vendor. Well, that's as long as your hardware is supported by the virtual server software. This will be an interesting area to watch, as hardware vendors do deals to improve functionality, and virtualisation vendors compete to provide ever more fully featured environments.

Even more interesting will be how this affects the way software is licensed. If virtualisation is used to manage peaks in demand, software licences may need to be renegotiated - otherwise they might be too expensive if, for example, the charge is based on a maximum usage that occurs only once a year to cope with a single spike in demand.

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