Marathon Makes Virtualization Fault Tolerant with v-Available

Published: April 18, 2007

by Timothy Prickett Morgan

Server virtualization hypervisors may not be used on every server today, but the technology is in the process of going mainstream on X64 servers after being on mainframe, proprietary midrange, and RISC/Unix servers for a number of years. And now, thanks to a partnership between fault tolerant server maker Marathon Technologies and XenSource, the commercial entity behind the open source Xen hypervisor for servers, it will be coming to servers equipped with Marathon's fault tolerant everRun software for X64 gear running Windows.

Unlike partners Stratus Technologies and NEC, which provide special fault tolerant versions of very specific X64 servers, Marathon's everRun software--which is itself a kind of virtualization software layer that abstracts the underlying software to provide fault tolerant on a two-node network of machines--will run on any Windows box. With fault tolerant setups, two machines are kept in exact lockstep and if any component of one machine or its software fails, the other machine in the cluster keeps running and users see no failure at all. This is distinct from other clustering approaches, which have a production system failing over to a hot standby system and replication software to keep applications and data synchronized.

Fault tolerant servers have, like other machines, been constructed out of physical server building blocks, but the advent of virtual machine hypervisors in the X64 space means that fault tolerance has to be thought of at a finer level of granularity. And that is what the v-Available initiative from Marathon is all about.

Marathon was formed in 1993 by some fault tolerant computing experts from the former Digital Equipment, who just so happened to be involved in the development of DEC's VAXft fault tolerant server line who saw a market opportunity for fault tolerant Windows servers when Microsoft launched Windows NT that year. Windows was not a very highly available operating system back then, which helped Marathon, and even as Windows has improved its availability through the generations, the demand for continuous uptime has grown among corporations. Marathon provides high availability products as well as fault tolerant configurations and a split-site disaster recovery configuration that can cluster Windows machines over a LAN or WAN. Marathon has over 1,200 customers, 125 resellers, and has just closed $12 million in second-round venture funding, and at least some of that money will be used to move the everRun products to Linux.

In the fault tolerant implementation of everRun, there is a thing called the everRun Virtual Server, which is the secret sauce that makes two physical servers look and act like one. This software virtualizes CPUs, memory, disks, and other I/O and provides the lockstep processing. The machines can be lashed together by Gigabit Ethernet links, or with faster networking if customers want higher bandwidth.

With the partnership, Marathon and XenSource are working to integrate XenEnterprise, the commercially supported version of the Xen hypervisor and management tools related to it, with the everRun FT software. Over the long haul, according to Gary Phillips, president and chief executive officer at Marathon, the v-Available extensions to the everRun products will allow Xen VMs to be delivering in a fault tolerant setup (meaning they run in lockstep on two physical servers) as well as in a high availability mode (where one VM will fail over to another) or in a split-site disaster recovery mode. The neat bit is that all of these different modes will be possible on a single pair of servers, so customers will be able to dial the level of recoverability they need for specific operating system and application sets residing on the physical hardware.

Right now, the v-Available extensions to everRun are only available for Xen, but Phillips says that Marathon will support the Viridian hypervisor that Microsoft has put into Longhorn Server. Because XenSource and Microsoft are working on Xen-Viridian interoperability, this support should come relatively easily. The everRun products do not support Microsoft's Virtual Server 2005 hypervisor, but Marathon has done some internal testing on it, according to Phillips.

"The challenge that we see is that you need to build an ecosystem around virtualization," explains Phillips. "We see a convergence of virtualization and high availability, which is good, but with all of your eggs in one basket, you need to be sure that virtual servers are as resilient as physical ones."

everRun DR will support the XenEnterprise implementation of the Xen hypervisor in the third quarter, which is also when Marathon will roll out its v-Availability assessment, design, and implementation services. In the third quarter, everRun FT will be Xen-aware, and after that, in 2008, Linux will also be supported. Marathon has not yet set pricing on the Xen-enabled products, but a license to everRun HA costs $7,500 (which is for two physical servers) and a license to everRun FT costs $16,000.

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