Microsoft has been busy refining the latest version of its virtualization hypervisor, Hyper-V Server 2008 R2. The product now supports live migrations, a clustered virtual machine file system, 64-bit operating systems, and machine specs similar to those of comparable VMware offerings.
With those heavy-duty features in place, it's a good time to look at how viable Hyper-V is as an alternative to VMware's market-leading ESX server virtualization platform. Below, we compare ESX with Hyper-V feature sets in eight critical categories
VMware has a big lead. In our August InformationWeek Analytics survey on virtualization management, in which we asked 316 business technology professionals which hypervisor is their organizations' main virtualization platform, 54% said ESX Server, 15% Hyper-V, and 7% Citrix XenServer.
Two declarations up front. One, I'm a virtualization engineer certified on VMware's vSphere 4.0 and have worked on many VMware implementations. That said, I approached this analysis determined to compare the two systems objectively. Two, the degree of functionality in the Microsoft offering surprised me. VMware is substantially more mature, but Hyper-V is a viable virtualization option now, and it's only going to get better.
1. High Availability
To make use of the products' high availability features, VMware and Microsoft require similar components--two or more virtual host servers with hypervisors installed, a centralized storage medium, and a management server. If a host fails, both systems can evacuate virtual machines to another available host in the cluster. Both systems also can migrate running guests from one node to another. However, VMware can do it for multiple hosts simultaneously, while Microsoft can move live guest machines only one at a time.
From experience, I know VMware has problems migrating large numbers of guests simultaneously and will do only three with the out-of-box configuration. However, this number can be adjusted if the vMotion network, which allows virtual machines to move on the fly, has sufficient bandwidth to replicate the contents of running memory for more than three machines without serious latency issues. VMware's vCenter management software also can be set to move workloads around based on host usage. Microsoft's product can do something similar, but it requires setting the machines up as resources in the cluster before they can be dynamically moved based on usage. This is an area in which VMware is a bit more polished.
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