Estimate: Amazon Cloud Backed by 450,000 Servers

amazon-racks

A slide of a data center from a presentation at the Amazon Technology Open House. (Source: James Hamilton)

How many servers does it take to power Amazon's huge cloud computing operation? Like many large Internet companies, Amazon doesn't disclose details of its infrastructure, including how many servers it uses. But a researcher estimates that Amazon Web Services is using at least 454,400 servers in seven data center hubs around the globe.

Huan Liu, a research manager at Accenture Technology Labs, analyzed Amazon's EC2 compute service using internal and external IP addresses, which he extrapolated to come up with estimates for the number of racks in each data center location. Liu then applied an assumption of 64 blade servers per rack - four 10U chassis, each holding eight blades - to arrive at the estimate.

That's one of several assumptions at the heart of Liu's estimate, which he notes in documenting his methodology, complete with caveats. Photos from a 2011 presentation by AWS Distinguished Engineer James Hamilton show 1U "pizza box" rackmount servers rather than blades, but it's not known if that was a recent depiction of Amazon's infrastructure (see Hamilton's presentation for more). But the server estimate seems feasible given Hamilton's assumption that an 8 megawatt data center could include 46,000 servers.

One interesting aspect of Liu's research is that it shows the concentration of Amazon's IP addresses in its US East region in northern Virginia, where Amazon maintains several data centers. He estimates that Amazon has 5,030 racks in northern Virginia, or about 70 percent of the estimated total of 7,100 racks for AWS. By contrast, the new Amazon US West (Oregon) region has just 41 racks, which are reportedly deployed in containers.

Liu's estimate is bound to generate some debate. But it provides an additional point of reference for Amazon's scale, along with earlier analyses from Randy Bias and Guy Rosen. It clearly places the size of Amazon's structure well above the hosting providers that have publicly disclosed their server counts, but still well below the estimated 900,000 servers in Google's data center network.