With all the buzz about virtualization in our world over the past few weeks (centered of course around Citrix's intention to acquire XenSource), I've been thinking about the "other" virtualization vendors in and wondering what they were going to do. This got me thinking to a company called "SWsoft" with a virtualization product they have called "Virtuozzo." I first learned about Virtuozzo when I was in Europe as part of the CDG roadshow. SWsoft was at a few of the shows, and I watched some of their presentations and talked to some of their engineers.
The reason that Virtuozzo sticks in my mind is because what they do truly is different. While all the other vendors do virtualization at the hardware level (i.e. they use virtualization to emulate a complete computer on which you can install any OS), Virtuozzo virtualizes an OS instance.
So what does that mean? Everyone understands that VMware virtualizes hardware. And everyone understands that SoftGrid virtualizes applications. Virtuozzo is kind of right in-between these two. So instead of Hardware Virtualization or Application Virtualization, Virtuozzo offers OS Virtualization.
In the Virtuozzo world, you install your base OS just like normal. (This can be Windows or Linux, but for the purposes of this article, we'll focus on Windows.) Once Windows is installed, you install Virtuozzo just like a regular application. Then from within the Virtuozzo console, you create multiple virtualization environments (VEs). These VEs each act as their own virtualized instances of Windows. They have their own IP addresses, their own security, and their own applications and configurations. But they're sharing the base OS instance. So when Microsoft releases an OS hotfix, you apply it once to the base OS instead of once to each VE instance. This OS Virtualization approach also gives you higher density than a HW virtualization solution since you're only running once Windows instance to be shared across all the VEs, instead of one per VE.
Of course OS Virtualization also has some downsides. The main one is that all VEs must be runing the same OS at the same hotfix / service pack / patch level. (Actually, some people list this as an advantage too.)
Given this about Virtuozzo, imagine how cool this would be for virtualized desktop environments? In these cases you wouldn't mind that all of the virtualized instances were Windows, and the fact that they share the OS with the host might also be a good thing. It seems that in terms of performance, this would be the way to go. So why didn't Citrix buy SWsoft instead? If it was Windows-only, that would certainly help the Citrix-Microsoft relationship, and since it's virtualizing at a different layer, it might not be too awkward between Citrix and Microsoft's Viridian.
Of course who knows whether SWsoft was even for sale? Or with XenSource costing $500m, who knows how much SWsoft would have cost?
What do you think? Have you used Virtuozzo before? Would you be more inclined to try that over a HW virtualization solution, or do you think it doesn't really matter with the low cost of today's hardware?