A while ago, I wrote about increasing interest in using fault tolerant platforms to support virtual environments. As organizations start thinking about moving truly critical business applications into the virtual world, I’d think that knowing those virtual workloads are running in a highly reliable environment would let a lot of IT professionals rest easier at night.

So it’s not surprising to see the fault tolerant systems vendors turn their attention toward moving their technology into the virtual realm. It’s also not surprising to see them turn toward Xen. The open source Xen hypervisor is getting some attention. Egenera chose Xen as the platform for its virtual environment management tool last fall. And late last year Stratus forged a partnership with XenSource to embed the Xen hypervisor into its fault tolerant technology.

Last week, Marathon Technologies announced a deal with XenSource (I wrote about Marathon last week). While Stratus and NEC sell specially designed fault-tolerant x86 systems, Marathon sells fault tolerant software.

Marathon’s software uses a virtualization layer to make two physical servers appear as a single system. Marathon executives say their software, which can run on unmodified Windows servers, reduces the cost and complexity of traditional clustering approaches.

I spoke with the Marathon executives last week about their plans. They say their focus moving forward will be on hardening virtual environments. Called v-Available, the initiative will result in a number of new products, the first being disaster recovery software for Windows-based virtual environments due out this summer.

“With our v-Available initiative, Marathon is addressing a major need, which is bringing availability to virtualization” says Steve Keilen, vice president of marketing at Marathon.

The upcoming products will be based on XenEnterprise, he says, though v-Available products also will support Microsoft’s virtualization technology, code-named Viridian, when it is released. Speaking of Viridian, check out an interesting story by my colleague John Fontana regarding the Viridian schedule.

Keilen says other products, enabling different levels of high availability and fault tolerance, will be rolling out through 2008. Support for Linux also is coming by the middle of next year, he says.

Get more details on v-Available here.