But measuring real-world capacity goes way beyond the basic numbers. Case in point: Both products now support the concept of dynamic memory, albeit in different manners. With Hyper-V 2012, you can configure individual VMs with an initial memory allocation and allow the hypervisor to adjust the amount of memory depending on current needs. This is not the default option when creating a new VM but a configuration setting. VMware has had this feature for several years, and the company claims much more real-world experience in the realm of memory utilization. Advantage here goes to VMware, but Microsoft has narrowed that gap substantially with Hyper-V 2012.
At the individual VM level, I used the Sandra 2013 benchmarking tool to determine basic numbers of performance from a single VM running Windows 7 SP1. This VM was configured to have 2GB of memory and two virtual CPUs. I ran four different benchmarks using Hyper-V 2008, Hyper-V 2012, vSphere 5.0, and vSphere 5.1. You can see from the table that Hyper-V 2012 holds its own against vSphere, at least with respect to running Windows VMs. Note that I did not test performance of Linux VMs. (Tests were run on a Dell PowerEdge R715 with dual AMD Opteron 6380 CPUs, 64GB of memory, and two Seagate ST9300605SS 10K 300GB SAS drives configured as a RAID1 array.)
The bottom lineFinally, one of the most difficult factors to compare is cost. If you're looking at a small number of virtualized servers running Windows Server 2012, you already get that with the purchase of the operating system. Windows Server 2012 Standard comes with two virtual instances, while Windows Server 2012 Datacenter includes an unlimited number of VMs on a single machine. It really doesn't make sense to purchase an additional virtualization product for a small-to-medium deployment.
VMware pricing starts at $4,495 for VMware vSphere Essentials Plus Kit, plus the vSphere Storage Appliance, covering three hosts with two CPUs each. Pricing for the central management system starts at $1,495 for the VMware vCenter Server Foundation, which supports up to three hosts. VMware vCenter Server Standard, which supports an unlimited number of hosts, costs $4,995. VMware vSphere with Operations Management bundles add deeper monitoring and automation capabilities; they start at $1,745 per processor.