Rackspace cloud storage general manager discusses the differences between private, public clouds

Emil Sayegh, GM for cloud storage at Rackspace, says the private cloud vs. public cloud issue confuses a lot of people, but both types can benefit certain computing workloads.

If you have trouble telling the difference between a private cloud and a public cloud, you're not alone. Emil Sayegh, Rackspace's general manager for cloud storage, said there's an important but poorly understood difference between the types of cloud computing available. Sayegh, who's in the process of merging the Mosso public cloud subsidiary back into Rackspace, recently spoke with SearchStorage.com about those differences and the long-term future of data storage in the cloud.

SearchStorage.com: We've started to hear a lot about cloud computing, but some of the terminology still seems to be confusing. What do the terms "private cloud" and "public cloud" mean from Rackspace's perspective? Is there a different target audience for private cloud vs. public cloud?

Sayegh: The two terms kind of get mashed together. To a lot of people watching this space it's kind of all a blob, it's all a cloud. For us, in a public cloud like Mosso, it's a set of computing resources shared among many people with virtualization technology that helps with securing and allocating resources.

The previous business that I managed [Rackspace's managed hosting] is a private cloud . You as the customer set up your own dedicated environment - you can spin up VMs [virtual machines], scale up or down within that environment, and pay according to a utility model.

From the public cloud side, everybody should be looking at the public cloud and using it, but it's not good for every workload. It's ideal for content, websites, SaaS [storage-as-a-service] applications … anything like a Wiki, a brochure site. If anybody's starting a project right now, whether a startup or new project in a big company, Mosso is ideal for that.

If you start getting into having a heavy database or custom apps, things like Oracle, that's more appropriate for a dedicated private cloud environment. If somebody's looking to outsource legacy applications, then private cloud or dedicated hosting will work for them. The big difference is that one is true pay-as-you-go and the other is one where you have to think more and make a commitment and put a contract in place.

Do you use different architectures at Rackspace to host private and public clouds?

Sayegh: Yes. Within Mosso we have three products – Cloud Servers, Cloud Files and Cloud Sites. There we use Xen servers. On the private hosted side, we also have a VMware-based Rackspace offering. VMware still has a long ways to go for it to work as public cloud software. You split off VMware [Version 3.5] management once the servers number into the few thousands. Thousands of instances are a lot for an enterprise – but for a service like Mosso, we need to scale at the hundreds of thousands of instances. With Xen, there are a lot of homegrown tools we can use. It's a much more open platform, and there's a lot of stuff we can do to customize it for a public cloud environment. With VMware, you're dealt a set of cards that they deal you.

On the private cloud side, of course we use EMC [Corp.] and Cisco [Systems Inc.] all day long. We have EMC SANs [storage-area networks] galore, but that's a different business from Mosso. That is catering to enterprises.

So what's the future of cloud computing? Will the public/private distinction persist?

Sayegh: The lines will blur as services evolve, and it won't happen right away – think 10 years. I will say the two will coexist for a long time because there are always going to be custom requirements that don't run on the cloud. But things are moving out of the data center – that trend is clear.

Look at power – there's probably no generator in your office building, but there's still a business for them, still a market for people who really need their own [generator] for places electricity doesn't reach. With cloud computing, eventually, more and more regulatory roadblocks are going to get resolved as cloud technology and regulations themselves evolve. Meanwhile, IT becomes more of a utility in and of itself, and something like Jungle Disk [which offers a Web-based GUI for public cloud storage on Mosso and Amazon S3 [Simple Storage Service]] becomes a common alternative for storage.

What does that mean for IT expertise? Do storage experts working inside companies today shift into these cloud computing data centers?

Sayegh: Instead of running storage, IT administrators are going to be making decisions as to what to run inside and what to run outside the company. They'll be more the arbiter of picking the technologies behind what they're going to be using. Dedicated, cloud, which is better? There are still going to be architecture decisions, but they aren't going to have to run it. I think that's a trend that's very real. From an opex standpoint it makes sense to CIOs. You architect it, it works, you go on to the next thing – improving it, not running it. That's what we're seeing happen. The mechanics of running [the infrastructure] is the variable here that gets removed.

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