Parallels has released a new version of its Virtuozzo container-based virtualisation software and said it will have a converged product later this year that will let customers run workloads using either containers or the more common hypervisor approach to virtualisation.

Virtuozzo Containers 4.0, now shipping, is the company's first release following its merger of the previously separate Parallels and SWsoft brands and their respective software lines.

With Virtuozzo, a server can be partitioned into several instances of the same operating system, the so-called containers approach. This makes more efficient use of resources than the hypervisor model used by rivals such as VMware, where each partition is an entire virtual machine.

Version 4.0 focuses on improving manageability, efficiency, and on aiding business continuity, according to Parallels chief executive Serguei Beloussov. "It allows customers to reach the greatest density of any virtualisation software, and we've tried to make management functions easier with each successive release," he said.

New features include real-time optimisation of hardware resources and support for clustering under Red Hat Linux and Windows Server 2003. Virtuozzo 4.0 also introduces a new tool, Parallels Infrastructure Manager, for controlling virtual environments in the datacentre. This only supports containers under Virtuozzo initially, but administrators will in future be able to manage virtual machines operated by third-party technology such as Microsoft's Hyper-V, Beloussov said.

Parallels also said that its Parallels Server product, currently in beta and due to ship in Q2 2008, will eventually be able to operate both its own native virtual machines and Virtuozzo containers on the same physical server. The company had previously hinted at such plans, but has now given a roadmap to this support for the first time.

"By the end of 2008, you will be able to take a virtual machine and restart it as a container, and vice versa," said Beloussov. He explained that both approaches have their advantages and disadvantages for particular applications.

"In testing and development, the hypervisor approach is right, but for other workloads like consolidation, and operating software-as-a-service environments, containers are the best," he said.

But Butler Group senior research analyst Roy Illsley said it was not immediately obvious what benefits this might offer.

"If you look at enterprise servers from the likes of IBM, they use partitioning to divide up and micro-manage resources, and I'd guess what Parallels might be doing is trying to bring that kind of capability to the x86 server market," he explained.

However, he warned that the profusion of virtualisation solutions now becoming available is leading to customer confusion over the right solution for their needs, and this move will only add to that.

Meanwhile, IBM has introduced a new version of its virtualisation software for Power-based Unix and Linux systems, aimed at firms seeking a less costly introduction to its more advanced features. PowerVM Express Edition lets customers create up to three partitions, and with its new PowerVM Lx86 feature, can also run many Linux x86 applications unmodified and without recompilation on System p servers.