Microsoft.com published a report on their results running virtualized MSDN and TechNet Hyper-V servers. Finally, someone steps up and says how much the overhead is for virtualization layer, 5 - 6%.
Dual socket Quad-Core Intel processors
4x146GB disk drives
4 Virtual processors
250GB dynamic VHD
Operating system – Parent
Windows Server 2008 Hyper-V RC0
Reserved 2GB RAM from 32GB total
Operating system – VMs
Windows Server 2008
Internet Information Services (IIS) 7.0
· Hyper-V CPU overhead (as measured by the parent partition utilization) was 5 to 6 percent with linear progression as the number of requests increased. This is illustrated in Figure 2.
· CPU oversubscription (three four-processor VMs on an eight-processor physical server) resulted in 3 percent lower overall performance per physical server based on overall requests per second per 1 percent CPU.
· Requests per second per 1 percent CPU performance of MSDN over the previous physical server platform improved. This demonstrates to us the viability of efficient consolidation from dedicated older physical servers to shared virtualized platforms.
· Physical MSDN handled 21 percent more requests per second per 1 percent CPU than virtualized MSDN. Figure 3 illustrates physical compared to virtual scale up for MSDN under peak production load on matching hardware.
· Based on our results with Hyper-V, and a review of current hardware utilization across our environment, we expect to realize significant benefits by consolidating diverse applications on a virtualized platform. Mixing high and low scale systems on the same physical server resources should enable us achieve improved overall hardware utilization and a reduced physical footprint.
· Although we reduced our hardware supporting MSDN and TechNet by migrating from older physical servers to a smaller deployment of new, more powerful physical servers, there is some minimal overhead associated with virtualization. From our perspective, Hyper-V has clearly delivered enough performance, stability, and scale to drive widespread adoption in our production environment. The flexibility and management gains expected from coupling System Center Virtual Machine Manager (SCVMM) v2 with Hyper-V should justify the measured overhead.
· If the three percent or less in additional overhead from oversubscribing resources is consistent with additional application workloads tested, oversubscription with Hyper-V should provide MSCOM Ops significant flexibility and reasonable performance for application consolidation.
· The results we achieved are based on the application characteristics of MSDN and TechNet on Hyper-V RC0. We are working to build a model based on this data that we hope will allow us to predict physical and VM requirements based on common performance characteristics of a Web site. The model will likely include the current requests per second per 1 percent CPU metric with additional memory and I/O performance characteristics as we virtualize other Web applications and gather more test and production data.