Microsoft has recently updated a TechNet page to illustrate the configuration limits of Hyper-V in W2008 R2.
Last week, I was asked by a local IT magazine to compare the limitations of VMware vSphere 4 to Hyper-V. But not the hosts; the virtual machines, i.e. how many processors, disks and RAM could I assign to a VM on either platform. I put together the numbers.
So for example, a VM in Hyper-V can have up to 4 processors and 64GB of RAM VS 8 processors and 255GB RAM on vSphere. At first impressions: WOW! VMware tramples all over Microsoft.
Hold on, let’s get real. How many VM’s have I ever run that needed that config? ZERO. The most RAM I’ve put in a VM is 8GB. The most virtual processors was 2. If I needed 8 cores and 64GB of RAM I’d question if the VM should be a VM at all!
OK, there’s cases where it would but they are rare. Microsoft runs MSDN/TechNet on Hyper-V and those specs were high. Maybe you might have 1 VM per host for DR reasons: the VM is more portable and easier to replicate than a physical machine.
But in the real world, most of us rarely have servers with huge needs. The only servers I’ve run with lots of RAM were Citrix/Terminal Servers and there’s a loss of performance for larger implementations if virtualised.
I don’t really care about those max limits for VM’s. They’re theoretical to me. I’m not going to get in any slagging match over them: I’ll leave that to the sort of person who debates the merits of Picard VS Kirk 😉