Again, all tests were conducted on the same physical hardware, with the same EqualLogic PS6010XV iSCSI array for storage, and on identical virtual machines built under each solution. All the Windows tests were run on Windows Server 2008 R2, and all the Linux tests were run on Red Hat Enterprise Linux 6 -- with the exception of Microsoft Hyper-V. Because Hyper-V does not support Red Hat Enterprise Linux 6, we used RHEL 5.5, which may have had a minor impact on Hyper-V's Linux test results.
The performance test results show the four hypervisors to be closely matched, with no big winners or losers. The main differences emerged in the loaded hypervisor tests, where XenServer's Windows performance and Hyper-V's Linux performance both suffered. Overall, VMware vSphere and Microsoft Hyper-V turned in the best Windows results [see table], while vSphere, Red Hat Enterprise Virtualization, and Citrix XenServer all posted solid Linux numbers [see table]. The crypto bandwidth tests, where XenServer and vSphere proved three times faster than Hyper-V and RHEV, showed the advantages of supporting the Intel Westmere CPU's AES-NI instructions. Charts of a few of these test results are displayed below.
Microsoft Hyper-V shined when running a Linux VM in isolation, but wasn't as consistent as the others at maintaining Linux performance when loaded with multiple active VMs.
Hyper-V certainly held its own in the bzip2 file compression tests, even when the hypervisor was stressed by multiple VMs.
Citrix XenServer often turned in the best raw Windows performance, but didn't always maintain it under a wide load. (The Sandra Whetstone benchmark measures floating point processing performance.)
Microsoft Hyper-V and VMware vSphere were the most consistent performers when running Windows VMs.
Citrix XenServer and VMware vSphere support the Intel Westmere CPU's AES-NI instructions, and Microsoft Hyper-V and Red Hat RHEV don't. It makes a big difference.
Virtualization shoot-out: Understanding the spread Although VMware still leads the pack in features, not all of them carry the same weight when placed in any given corporate environment. Three features that will matter to environments of any size are live VM migrations, high availability, and load balancing.
Live migrations are the ability to move running virtual machines from host to host without rebooting. High availability allows a solution to determine when a physical host is down and automatically restart the virtual machines that were running on that host elsewhere in the farm. Automated workload balancing levels the VM load across multiple farm servers based on thresholds set by administrators. These are key features that once were available only from VMware, but are now present in each solution.
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