Parallels is entering the desktop virtualisation market with its Virtuozzo container-based platform, which enables customers to support more users per server than other virtualisation tools, according to the company.

Virtuozzo Containers is already used in datacentres for server consolidation, but Parallels has now announced a partnership with Quest Software’s Provision Networks division, adding desktop broker and image management tools that turn it into an end-to-end stack for virtualising client systems as well.

While desktop virtualisation tools are already available from vendors such as VMware and Citrix, Parallels said that Virtuozzo Containers is more efficient as it virtualises at the operating system level; it creates multiple instances of the underlying host platform while the rival hypervisor approach creates entire virtual machines.

"With a hypervisor, you lose lots of efficiency, and so you might get 10 virtual machines on a $20,000 server. That means that instead of spending $500 per user [on a desktop PC], you're suddenly spending $2,000," said Parallels chief executive Serguei Beloussov.

With Virtuozzo Containers, enterprise firms can support five times as many users on the same hardware, he claimed, which translates into the ability to support the same number of workers using fewer servers than rival virtual desktop systems.

Another advantage of the containers-based approach of Virtuozzo is that it simplifies patching for administrators, as any patches applied to the host affect the containers as well.

A typical deployment will use Windows Server 2003 as the host, but templates applied to the containers mean that users see the XP desktop, according to Beloussov.

"Windows XP and Windows Server have the same kernel. Users are getting Windows Server kernel, but the package set (Parallels Virtuozzo Template) makes it look like Windows XP for all intents and purposes," he said.

Butler Group senior research analyst Roy Illsley agreed that the container-based approach has scalability and patching advantages, but said there are also drawbacks.

"The containers are not as well isolated from each other as the virtual machines are with a hypervisor – it is basically the same OS sliced up," he said. It is possible that a problem might develop in one container and bring down the host, he added.

This may not be a problem if workers are just running productivity applications, Illsley said, and so a company may decide the cost savings outweigh the risk of occasionally having to re-boot the host server for some users.

The real challenge, according to Illsley, is management.

"If you have a mix of VMware, Parallels and Microsoft virtual machines, how do you oversee the lot of them? No single management tool supports all of these platforms," he explained.

The new virtual desktop package is available immediately from either Quest or Parallels and uses Virtuozzo as the virtualisation layer while Virtual Access Suite (VAS) provides user access and management of the virtual clients. It costs £86 per user, plus £17.20 per user for one year's maintenance.