Marathon Offers Low-Cost Fault Tolerance Solution

In a unique combination of fault tolerant computing and virtualization, Littleton, Mass.-based Marathon Technologies Corp. has developed a low-cost fault tolerant solution that utilizes standard hardware while supporting virtualized servers. The company's technology stretches a virtualization layer across two identical servers running Windows Server. This layer takes any interaction with the OS or its application and duplicates it across the two servers. Also, server processors run in lockstep with each other, thereby returning identical results simultaneously. If one server fails at any point, the results from the second server are used alone.

Marathon owns several patents on the technology behind enabling the processors on separate servers to execute in lockstep. Think about it: If one of the servers goes down, not a single processor cycle is lost. Most fault tolerant solutions work by doubling up on system hardware, but are unable to maintain accuracy down to the level of a single processor cycle in the event of a failure.

This is impressive, but it's not where the virtualization comes in. At the recent VMworld conference, Marathon won the Best of VMworld Award for New Technology. This technology, called everRun for XenSource's XenEnterprise v4, provides the ability to do the same level of fault tolerance not across two physical servers, but across two separate virtual machines (VMs). Those VMs run on two separate servers, so that if one fails, the VM running on the second physical server provides the same processor cycle accuracy for the running applications.

This also works for multiple VMs running on one physical server, paired with identical VMs running on another physical server, or the collection of paired VMs that can be running on several different servers. Marathon's everRun requires a dedicated gigabit Ethernet connection between the two servers and a guaranteed 10ms response time across the connection. This means that the physical servers can be geographically separate. Marathon officials say the longest distance between servers in a customer deployment is about 100 miles.

Perhaps the best news is that Microsoft considers those paired identical Windows Server installations, executing in lockstep, to be a single Windows Server license. The Windows Server installation is actually the same instance, duplicated across separate physical boxes.

About the Author

Peter Varhol is the executive editor, reviews of Redmond magazine and has more than 20 years of experience as a software developer, software product manager and technology writer. He has graduate degrees in computer science and mathematics, and has taught both subjects at the university level.


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