VMware’s Eric Horschman is making hay in the blogosphere with a post that proclaims VMware to be more cost effective than low-cost/free hypervisors like Hyper-V and Xen. Horschman writes:
“Our competition and a few industry observers have lately taken up the sport of bashing VMware Infrastructure as overpriced. Microsoft is playing up their plans to bundle Hyper-V with Windows Server 2008 as a way undercut VI3 pricing and jump-start their late entry in the virtualization market. One of our Xen-based competitors has even adopted a marketing tag line of “one-fifth the cost of comparable alternatives,” clearly referring to us.”
(The competitor is Virtual Iron.)
Horschman says that VMware bests the others when looking at “cost per virtual machine.” Essentially he argues that because VMware Infrastructure software can trick a server’s memory into sharing memory beyond typical tolerances, VMware can run double or more the number of virtual machines on a server without a performance hit. This gives it the lowest cost per VM, even when considering a license fee of over $5K for the virtualization software, he says.
He says cost per VM is measured by adding up the costs of the server, operating system, virtualization software, application software and then figuring out the maximum number of VMs the server can handle running your workload. When you’ve filled the server up with so many VMs they can’t perform to your service requirements, you’ve got your max and your cost per.
Of course, VMware ran its own test.
“We took a common dual socket server with 4GB of RAM and tried the test with ESX Server 3, Citrix XenServer v4 and Microsoft Hyper-V beta. We created and powered on 512MB Windows XP VMs running a light workload and kept adding them until the server couldn’t take any more. Our Hyper-V and XenServer tests topped out at six and seven VMs respectively, which was expected. You see, both those products subtract the full amount of memory allocated to each running VM from the host’s physical RAM.”
After a lengthy discussion of exactly how VMware ESX Server tricks the server into what VMware calls “overcommitting” memory, Horschman says that the VMware software hosted as many as 40 VMs running light workloads. However he also notes that when the VMs are expected to handle heavy workloads, the server admin would never overcommit memory at such a high rate. A more “conservative” use of memory (a 2:1 ratio) he says, would lead to 14 VMs on a 2-way 4G sever – roughly double the number of VMs than the competitors he tested.
ChannelWeb blogger Ed Moltzen points out that 4G is the minimum for running Windows Server 2008 and that most resellers recommend loading up servers with far more RAM than that. So, if you spent the money on more RAM, say doubling it to 8G for an additional $600 or so, presumably you could double the number of VMs on the box (free or otherwise).
One question then becomes will 14 hypervisors at an additional cost of about $600 for 8G RAM meet your requirements as well as 14 hypervisors using VMware ESX Server at a cost of over $5,000 on a server with 4G RAM?
Another question is how hard a performance hit your VMs will take when pushing the overcommit limits of your particular workload on your particular software?
Clearly, there are ways to show that Horschman’s case is pure marketing – benchmarked in exactly the right way to show VMware as the best deal. On the other hand, he does have a point. There are most definitely ways to do an initial install cheaper using lower-cost hypervisors. But because VMware’s technology is ahead of the market (most folks would agree), it may be less expensive in the long run for many companies.
This, of course, won’t stop Hyper-V from making inroads, seeing that it ships with Windows Server 2008. Because enterprises will have it on hand, it certainly doesn’t cost them much to toss it in the lab and see how it does. this story by Jon Brodkin.
For a full list of all the virtualization competitors out there, check out
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