"I'm a cloud architect," says Carl Perry, and there's not even a hint of irony. His business card says the same thing.
Perry works for a Los Angeles outfit called DreamHost. The company began life in 1997 as a four-person operation that would set up and host websites for anybody who needed one, but like many web hosts, it has evolved into something a bit different. Following in the footsteps of Amazon, Google, and Microsoft, it's now offering what are commonly known as cloud services -- internet services that give you instant access to computing power.
With these services -- named after Amazon's seminal Elastic Compute Cloud -- you can set up and host a website all on your own. Or fire up any other software application. Or store virtually unlimited amounts of data.
Carl Perry calls himself a cloud architect because, well, he oversees the creation of these DreamHost services -- from servers to networking gear to software. But the title means a bit more than that. These services, you see, aren't built like traditional web services or other online applications. They're designed to share a common computing infrastructure with a vast number of outside developers and businesses -- and rapidly expand with the needs of these users. This requires an added level of coordination between machines -- and some extra attention to cost.
The software is different. The hardware is different. And in some cases, the hardware is arranged in a very different way. "We've tried to come up with a plan for how to integrate all our equipment -- and make it modular and flexible and high-speed," Perry says.
Inextricably tied to the internet hype machine, cloud computing is a difficult concept to pin down. The term has come to mean almost anything. But there are cases where it represents a very real change not only in how computing power is accessed, but in how data center infrastructure is built. Carl Perry is just one of many "cloud architects" popping up across the tech world -- at companies as diverse as DreamHost and eBay and even HP -- and though the name may mean very little with some, it means a great deal with others.
Anatomy of a DreamHost
Carl Perry and DreamHost build their cloud services much like Google and Amazon. They use low-cost commodity hardware -- including gear purchased directly from manufacturers in Asia -- and then they handle all the complex stuff with software.
DreamHost's cloud service -- which is still in the "beta" testing phase -- doesn't give you dedicated access to individual servers. Using an open source platform called OpenStack, it gives you access to virtual servers -- machines that exist only as software. Basically, the company can pack multiple virtual machines onto each physical server, and these virtual machines can operate independently of the hardware running beneath them. You can then use these virtual machines to run whatever software you like.
Virtual machines are nothing new. But DreamHost goes a step further. It's an early customer of Nicira, a startup recently purchased by virtual server kingpin VMware for $1.26bn. Nicira provides a means of tying virtual machines together into a complex virtual network. Using the Nicira network controller -- a piece of software -- DreamHost can program its network in much the same way we program computers. The company can make complex changes to the network via software, as opposed to reconfiguring its hardware.
It can more easily isolate the network traffic of each business that uses the service -- keeping the traffic that belongs to one business separate from that of another -- but it can also give those many businesses the opportunity to fashion their own particular networking schemes atop the service. "It gives us the flexibility to support hundreds of thousands of tenants on the network -- as opposed to 4,096," Perry says.
Of course, you still need a physical network running beneath these virtual networks. But with the Nicira controller, DreamHost can also simplify its physical network and reduce the cost of the hardware -- something that's essential when you're operating a service designed to expand so quickly with the needs of its users.
With Nicira, the physical network is mainly just a means of forwarding traffic. The complexity lies in software. DreamHost doesn't need high-end networking gear from the likes of Cisco and Juniper and HP. It uses less expensive hardware from Silicon Valley startup Arista, and in an effort to cut additional costs -- much like Amazon and Google -- it's even buying gear directly from Asian manufacturers Delta and Accton, some of the same manufacturers that build gear for the likes of Cisco and HP.
Buying and configuring this sort of "white box" hardware isn't the easiest thing to do -- you don't the handholding provided by a Cisco or an HP -- but at DreamHost, the arrangement is facilitated by a company called Cumulus Networks. Cumulus exists solely to make it easier for companies to use low-cost networking gear that comes straight from Asian ODMs, or original design manufacturers.
The Spine and the Leaves
The DreamHost network even looks different.
Traditionally, data center networks are built like bicycle wheels. In essence, there's a network hub with spokes running to each rack of machines. Lines run from a network "core" to a switch at the top of each rack.
But the networking that underpins DreamHost's cloud service uses what Perry calls it a "spine and leaf" architecture. Basically, this flattens the network. Rather than operating from a central hub, the network is built around a long spine that runs from rack to rack. The racks are the leaves.
>'We now see a lot of what we call east-west traffic -- traffic within the data center, as opposed to traffic between the server and the user.'
Martin Casado
What this does is make it easier for traffic to travel between servers, and that's what's needed for the sort modern web service DreamHost offers. "Today, when a request comes into a web server, it will also touch three hundred other servers," says Nicira founder Martin Casado, who has seen many customer adopt this setup, "and because of that, we now see a lot of what we call east-west traffic -- traffic within the data center, as opposed to traffic between the server and the user."
This also makes it easier to expand the network -- and cut costs even further. You don't need a lot of the gear you would typically use in the network core. All you need is the sort of low-cost switches -- known as pizza-box switches -- that DreamHost purchases straight from Asia. Each server rack has a pizza box switch that connects it to the network, and there's a second tier of these same switches that serve as the network spine.
"This lets us deploy quickly and expand quickly," says Perry. "We don't have a core, and all our switches look exactly the same. Deploying more of them? Not a problem."
When a Cloud Is Not a Cloud
DreamHost is just one of a growing number of companies that are rebuilding their computing infrastructure in the vein of Amazon and Google. In some cases, companies are offering up this infrastructure to the rest of the world as cloud services, including Rackspace (which provides services very similar to DreamHost's) and Cloudfare (which offers a content delivery network that lets you speed up the delivery of webpages to users across the globe). But other outfits are rebuilding so that they can offer similar services for use within their own companies.
One example is eBay. J.C. Martin is a "cloud architect" at the online auction house, and his network looks a lot like the one at DreamHost. It too uses Nicira atop a spine-and-leaf network. eBay doesn't provide a cloud service to outside companies, but in similar fashion, Martin serves up infrastructure to eBay teams working across the company's marketplace business.
"We can innovate more rapidly," Martin says, "and then offer that innovation to the rest of the company as services."
Some insist these shouldn't be called cloud services. Companies like Amazon only use the metaphor to describe web services that outsiders access from afar. But it doesn't matter what you call it.
You can roll your eyes at the metaphor. You can scoff at the notion of a cloud architect. But the fact of the matter is that eBay and DreamHost have built their networks in much the same way -- a way that departs from data center designs of the past. And these two are not alone.
Photo: Nhi Dang/Flickr
