Virtualization shoot-out: Citrix, Microsoft, Red Hat, and VMware

In data centers large and small, the move to server virtualization seems as unstoppable as the waves crashing on the beach in Hawaii's Waimea Bay. But for almost as long as the virtualization tide has been rising, there was only one vendor that could offer the features, interoperability, and stability necessary to bring virtual servers out of the skunkworks and into daily production. That is no longer the case.

From the beginning, VMware has been the king of x86 server virtualization, hands down. VMware's feature set, reputation, and pricing all reflect that fact. But where there used to be little competition, you'll now find a select group of challengers that have brought a wealth of enterprise features to their virtualization solutions and begun to give VMware a run for its money.

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In order to accurately gauge just how close this race has become, we invited Citrix, Microsoft, Red Hat, and VMware to the Advanced Network Computing Lab at the University of Hawaii, and we put their server virtualization solutions to the test. We compared Citrix XenServer, Microsoft Windows Server 2008 R2 Hyper-V, Red Hat Enterprise Virtualization, and VMware vSphere by virtually every measure, from ease of installation to hypervisor performance, and all of the management capabilities in between.

We tested each solution on the same hardware, with the same real-world network topology, running the same tests on the same virtual machines. We ran real-world and synthetic Linux and Windows performance benchmarks, and we performed subjective management and administration tests. We looked at host configuration, VM templating and cloning, updates and patching, snapshots and backups, and scripting options, and we examined advanced features such as load balancing and high availability.

The results showed that all four solutions combine very good hypervisor performance with rich sets of management tools. But the solutions are not all equal in either performance or management. Although VMware is no longer the only game in town, choosing an alternative certainly involves trade-offs.

VMware still has advanced capabilities that the others lack. VMware also offers a level of consistency and polish that the other solutions don't yet match. The rough edges and quirks in Citrix, Microsoft, and Red Hat aren't showstoppers, but they demonstrate that these alternatives all have hidden costs to go along with their (potentially) lower price tags.