The data center will never be 100% virtualized, as some database, transaction, and legacy systems resist being consolidated on virtualized servers. But a recent survey of 554 companies had 92% of companies saying they're making use of some form of virtualization and, on average, they've virtualized 39% of the servers in their data center.
With a little over one-third of the data center converted, there's still room for more x86 workloads to be migrated to virtualized hosts. That means more energy and capital expense savings to be realized, as stacking applications in virtual machines on a host tends to allow some servers to be phased out.
Veeam, a third party supplier of management and backup tools to the VMware market, sponsored the survey. It hired Vanson Bourne, a U.K. independent market researcher, to query companies with more than 1,000 employees each in the U.S., U.K., Germany, and France. The CIO, someone on the CIO's staff or high level IT managers were the target respondents.
The average number of virtual machines per server is six, the survey found. That's less than the maximum possible but not surprising. When implementing virtualization, most data center managers don't want to test the limits of how many virtual machines may run on a single host. Even if memory and CPU are sufficient for more VMs, there are still clog points at I/O or nearby network devices that can slow operations.
The most accomplished virtualization implementers, such as an Accenture or managed hosting suppliers, may stack 20 or 30 virtual machines on the latest version of an Intel multi-core server. But many virtualization implementers don't want to move to high end, x86 servers. They want to stick to their bread and butter two-way and four-way models and get the highest possible utilization out of them. It also takes lots of experience to accurately prejudge application conflicts on a host--is the database traffic for back up purposes late at night or is it going to occur in the highest customer traffic portion of the day? Mixing and matching applications on a server is still an art, not a science.
Veeam's survey did contain one surprise: the prevalence of multi-hypervisor environments. Overall, 84% of those surveyed use VMware, 61% use Microsoft Hyper-V, and 55% Citrix Systems' XenServer, 12% use some other hypervisor, including Red Hat's KVM. When it comes to the "primary hypervisor" used, Citrix ran slightly ahead of Microsoft. Citrix represented 20.2% of hypervisor use, compared to Hyper-V's 18.6%. Needless to say, VMware, the market leader with its ESX Server, was out in front at 58.2%.
I find the Citrix figure is somewhat contrary to what Gartner and Microsoft itself have tended to say--that Microsoft is already the likely number two virtualization vendor or about to become number two behind VMware. On some occasions, Gartner has tended to talk about Microsoft and VMware dividing up the bulk of the market between them, as in its November 2009 report: "Virtualization with VMware or Hyper-V: What You Need to Know." More recently, it included both Microsoft and Citrix Systems in its virtualization Magic Quadrant. Still, Citrix, which had a much smaller base of customers coming into the virtualization market than Microsoft, is showing surprising resiliency at 20.2%.
Citrix came into the virtualization market with established strength in virtualizing Windows applications on central servers and providing application services to thousands of end users at a time. This was a one-size fits all approach; each end user got the same service and the same level of performance. But it's been able to translate that success into expertise in more sophisticated end user virtualization today and is competing hard with VMware on that front, as cited in this account of the "personal cloud" at Indiana University.
I would also say that Citrix acquired a high degree of credibility in virtualization expertise with its acquisition of XenSource, founded by Ian Pratt and Simon Crosby, originators of the Xen hypervisor. The pair resigned in June to found a virtualization security startup, Bromium. I think they are likely to continue to work closely with Citrix, which is collaborating with the National Defense Intelligence Agency and U.S. Air Force on secure virtualized client operations.
Veeam is using the survey to establish a community site that will conduct periodic surveys and update virtualization's level of enterprise penetration. As a company that's built its business selling into VMware environments, it could be suspected of bias, but product strategist Rick Vanover says Veeam plans to support Hyper-V with its core Backup & Replication product later this year.
Gartner said recently that Microsoft is capturing one in three mid-market customers for Hyper-V. Part of its success has to be linked to the fact that Hyper-V is built into Windows Server 2008 Release 2 and is freely available to Windows Server users. VMware, in contrast, charges $1,540 for two CPUs for ESX Server in a supported, baseline system. So far, however, free has not been enough to give Microsoft a large share of the high end, production marketplace. Its growth will be inexorable at the department level, among development teams and in small companies, where free is a deciding factor.
Citrix and VMware are showing persistent strength in virtualizing production systems with products that are separate from the operating system. It will be an interesting to see customers continue to keep them in that position or begin to shift toward a more commodity--let the operating system's hypervisor do it--approach. V-index.com may become a leading indicator of the direction of virtualization.
Charles Babcock is an editor-at-large for InformationWeek.
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