Is virtualization technology really ready to handle your mission-critical applications, or is that just foolish, foolish, wishful thinking? It's an important question because there's definitely a feeling in the air that the time to virtualize everything has finally come. You can almost smell the inevitability of it.
As you'd imagine, VMware is rubbing its corporate hands with glee at the prospect while making itself busy encouraging anyone who wants to listen. Talking at the VMware Forum 2011 in London earlier this month, David Burgess, a VMware solution architect, argued that it's not just that you could virtualize your mission-criticals -- it's more that you should. Running business-critical applications on physical, non-virtualized servers is actually bad for business, he'd have you believe. And perhaps he has a point.
Of course, Burgess works for VMware, so he's paid to take that view, but that doesn't mean it's not worth listening to him and making up your own mind. One of his key points is that 95 percent of mission-critical applications (as he defines them) can't make use of all the resources of the physical servers on which they run. "If you look at it, most of these applications can't scale beyond two to four cores," Burgess said. Since the performance of the applications running in VMs is about the same as those running on physical servers, he maintains, what's the argument against server virtualization? "Running business-critical apps in a physical environment is simply not sustainable," he said.
His argument doesn't end there, though. He points out that with a physical approach, you need a custom solution for each of your mission-critical application stacks to provide high availability, disaster recovery, data protection and so on. That's complex and expensive, and it requires skilled specialist staff to configure and manage each one.
Burgess argued that that's not necessary with server virtualization -- at least using VMware's hypervisor. "High availability, fault tolerance, data recovery -- they are all baked in to the virtualization solution," he said. Instead of individual application silos, he described a setup with numerous mission-critical applications running on vSphere on two or three physical servers. Local availability is provided by VMware High Availability (to restart a VM on a new server when a server or operating system failure is detected) and Fault Tolerance (for instant failover), plus Vmotion and Storage Vmotion when necessary. There's also VMware Data Recovery and vStorage APIs for Data Protection for backup and recovery, plus vCenter Site Recovery Manager for site protection using array-based replication.
Even if you accept the arguments so far, many companies are reluctant to go virtual with their mission-crits because they're worried about support. Burgess' answer to this objection is basically that if your application vendor doesn't support running the app in a virtual environment, it's making a big mistake.
How does he come to this conclusion? Because big software companies like SAP, Oracle, Microsoft and IBM support VMware's virtualization technologies, along with 1,400 other ISVs. Plus, let's not forget that many companies actually develop their applications in VMs. Certifying an application for use in a VMware virtual machine can be less of a headache than having to certify it on many different physical servers, he added. Ultimately, Burgess buys into the VM crossover argument: In 2009 more workloads ran in VMs than physical hosts. "If your ISV is not on board with virtualization now, then maybe they don't have the vision to support you going forward." Ditch 'em, in other words.
What about license costs? This can be a problem, but it shouldn't be, Burgess reckoned. "The industry is behind the curve on licensing, and some ISVs try to exploit virtual infrastructure to argue for an increase in license costs. But in every case this can be negotiated away, and I think over time this problem will go away," he asserted with confidence. In general, it's probably fair to say that virtualization leads to workloads running on less processor cores, and features like vSphere's DRS (Distributed Resource Scheduler) VM to Host Affinity Rules make it possible to restrict VM movements to licensed hosts in a cluster. That eliminates the need for dedicated clusters and ensures an application licensed to run on a single CPU server doesn't end up on a dual-CPU host.
Server virtualization is now a relatively mature technology, and the challenges and benefits are certainly well understood, as this recent Symantec study 2011 Virtualization Evolution to the Cloud made clear. With the various parts of the jigsaw needed to support it (e.g., security or management) rapidly falling into place, the most important question to ask may not be if you should virtualize your mission-critical applications, but when?
Paul Rubens is a journalist based in Marlow on Thames, England. He has been programming, tinkering and generally sitting in front of computer screens since his first encounter with a DEC PDP-11 in 1979.