VIRTUALIZATION

Steve Herrod, Mike Neil from Microsoft, and I have been working on an emerging standard called OVF (Open Virtual Machine Format) to define a common abstraction to package applications into a container. Under this definition, an application is some number of template VMs, plus all the metadata about how much resource they need, how they’re interconnected, and how they should be instantiated.

We started working on it because there was the potential for a VHS-versus-Betamax virtual-hard-disk format war, and none of us wanted that to happen. It started out as a portable virtual-machine format but is now emerging into more of an application description language. The container has one instance of every component of the application, but when you roll it out at runtime you may request multiple copies. I think that’s a very important step forward in terms of standardization. HERROD Virtualization breaks up something that has been unnaturally tied together. However, allowing late binding introduces some new problems. If you cannot be more efficient with virtualization, then you shouldn’t be using it.

We do surveys every single year on the number of workloads per administrator. Our numbers are generally good, but it is because we effectively treat a server as a document and apply well-known document-management procedures to gain efficiencies. This approach forces you to put processes around things that did not have them before. For smaller companies that don’t have provisioning infrastructure in place, it allows much better management control. It’s not a substitute for the planning part, but rather a tool that lets you wrap these procedures in a better way. CREEGER How do people decide whether to choose VMware, Citrix, or Microsoft? How are people going to architect data centers with all the varying choices? Given that the vendors are just starting to talk about standards and that no agreements on benchmarking exist, on what basis are people expected to make architectural commitments?

GUSTAV I think this is a place where the technology is ready enough for operations, but there are enough different management/software theories out there that I fully expect to have VMware, Microsoft, and Xen in different forms in my environment. That doesn’t concern me nearly as much as having both SuSE and Red Hat in my environment.

BISHOP Every customer we talk to says they’ll have at least three.

CREEGER As a large enterprise customer, aren’t you worried about having isolated islands of functionality? GUSTAV No, I have HP and Dell. That’s a desirable case. CREEGER But that’s different. They have the x86 platform; it’s relatively standardized.

CROSBY It’s not. You’ll never move a VM between AMD and Intel—not unless you’re foolhardy. They have different floating-point resolution and a whole bunch of other architectural differences.

People tend to buy a set of servers for a particular workload, virtualize the lot, and run that workload on those newly virtualized machines. If we treated all platforms as generic, things would break. AMD and Intel cannot afford to allow themselves to become undifferentiated commodities; and moreover, they have a legitimate need to innovate below the “virtual hardware line.” CREEGER So are you saying that I’m going to spec a data center for a specific workload—spec it at peak, which is expensive—and keep all those assets in place specifically for that load? Doesn’t that fly in the face of the discussions about minimizing capital costs, flexibility, workload migration, and high-asset utilization? BISHOP You’re making an assumption that every business defines risk in the same way. Gustav defines risk in a particular way that says, “The cost of excess capacity is minuscule compared with the risk of not having the service at the right time.” CREEGER In financial services, that’s true, but there are other people who can’t support that kind of value proposition for their assets. CROSBY That’s an availability argument, where the trade-off is between having the service highly available on one