Virtualization shoot-out: Microsoft Windows Server 2008 R2 Hyper-V

Microsoft's server virtualization platform pairs good performance with extensive management, at the cost of significant added complexity

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Hyper-V R2 performance
We tested Hyper-V performance under Windows and Linux VMs, both with and without other VM loads on the physical server. A significant caveat to this was that Hyper-V does not yet support Red Hat Enterprise Linux 6, so all of these tests were conducted on RHEL 5.5 with Microsoft's Linux Integration Services for Hyper-V tools installed. Thus, while the numbers can be said to be similar to the other vendors, this discrepancy prevents direct performance comparisons.

That said, the Hyper-V performance tests showed impressive improvement of Linux guests versus the last time I took a close look. In thread-per-thread comparisons between the physical server and a VM, both running Red Hat Enterprise Linux 5.5, the VM ran with a 3 to 4 percent overhead depending on the test, which is quite acceptable. We did experience two kernel panic events related to the Microsoft driver code (the Linux Integration Services components) on the RHEL 5.5 VMs, but they were sporadic and not repeatable. A heavy-duty, 16-hour run of three four-vCPU RHEL VMs did not result in another problem.

Microsoft Hyper-V performed quite well in the benchmarks overall, posting very competitive numbers in both the Linux and Windows tests. One exception was the crypto benchmark, which tested cryptography speed of the virtual machine. While the VMware and Citrix solutions were posting numbers around 1.6GBps in these tests, Hyper-V consistently hovered around 500MBps. This significant lag in AES performance is due to the fact that, unlike VMware and Citrix, Hyper-V doesn't expose the AES-NI instructions in the Intel Westmere CPU to the VMs.

The intercore bandwidth and latency tests were very close to those of VMware, and the memory tests were actually higher than the rest of the pack. All this points to the fact that Microsoft has definitely made strides in VM performance, especially on the Linux side of the coin.

Hyper-V has come a long way in providing enterprise-class features and delivering enterprise-class performance. However, one aspect of Hyper-V that cannot be overlooked is the reliance on a cast of supporting players. Once you add up all the Operations Manager VMs, the SQL Server VMs supporting the Virtual Machine Manager VMs, and the Configuration Manager VMs, you find yourself running eight VMs just to support your other VMs. On top of that, some of these management VMs consume vast amounts of RAM for what they're doing.

As an example, with only a dozen or so VMs in play across three active hosts, the SQL Server VM was consuming 6GB of RAM and would take more if allowed. To a degree, you might consider that you'll be dedicating the equivalent of an entire host server's resources to the management VMs for a Hyper-V implementation of any size -- and I'm not even counting the domain controllers and other general-purpose servers that are required. As a contrast, VMware manages to incorporate all of these functions in a single vCenter Server instance, possibly with an accompanying SQL Server if the implementation is large enough.

So has Hyper-V finally reached critical mass for corporate deployment? Yes. Is it more confusing and involved to implement, manage, and operate than other solutions? Yes. Is it significantly less expensive than VMware? Absolutely. If you're a Windows-only house and you buy into Microsoft's Windows Server 2008 R2 Datacenter edition, which allows for unlimited VMs per host, you can save a ton of money over VMware. It'll also require more elbow grease to run and offer fewer high-end features than VMware, but at this stage in the game, that may finally be an acceptable trade-off for the right infrastructure.

Read the main article and the other reviews:

This article, "Virtualization shoot-out: Microsoft Windows Server 2008 R2 Hyper-V," was originally published at Follow the latest developments in virtualization and cloud computing at For the latest business technology news, follow on Twitter.

Copyright © 2011 IDG Communications, Inc.

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