If we were having a discussion based on cost alone and didn't have to bring features and management tools into the discussion, Hyper-V would already be the leading virtualizaton product compared to EMC VMware's vSphere. But obviously, money isn't the only factor when making the decision on which vendor to choose for your virtualization needs. That's why VMware has done so well.
But I believe that equation will change when Windows 8 Server comes out.
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So what makes me think Hyper-V is ready to make a significant move in the rankings? Well, there will be significant enhancements in Windows 8 Server. These may not surpass VMware's functionality, but the fact that these are all included in Hyper-V at no additional cost certainly makes for a more competitive and, in some cases, winning solution. Here are the enhancements that I believe will tip the balance in Hyper-V's favor at many organizations:
Scalability hikes: Support for 160 logical processors per host with 2TB of memory per host, 32 virtual processors per virtual system, 512GB of memory per virtual machine, and the new VHDX format all makes for impressive scalability improvements in Hyper-V. They remove the barrier that Hyper-V now has in terms of inadequate performance as the use scales.
New VHDX format: The new virtual drive format allows for larger block sizes (16TB, up from 2TB limit for VHDfiles).
Storage enhancements: There is an addition of virtual Fibre Channel for virtual guests. Clusters can connect to SAN fabrics through HBAs on the physical host, and you can have as many as four virtual HBAs per virtual machine. The new Storage Live Migration feature lets you move virtual disks between different types of storage (NAS, DAS, and SAN) when you need more space -- without users losing connectivity.
Networking enhancements: Hyper-V in Windows 8 Server offers a new, extensible virtual switch that allows third-party switches to work with the Windows 8 Server network. By contrast, VMware today advertises only that it works with Cisco switches. NIC teaming has also been added into the feature set (to be fair, VMware has supported NIC teaming for some time).