AWS claims to have hundreds of thousands of customers, both large and startup-size, in more than 190 countries. AWS Simple Storage Service, for example, stores more than 339 billion online objects and peaks at more than 200,000 transactions per second. The primary benefit to Netflix, Dropbox, the European Space Agency (ESA), Yelp and other customers is that they are paying for exactly the computer resources that they use, whereas many in-house information technology departments are considered efficient if they are using more than 20 percent of their data center resources, Singh says.
Security and stability is always an issue when one company hands over its crown jewels (data, in particular) to another company. One danger is that the cloud service provider will crash, taking down customer Web sites with it. This happened to Amazon recently when the company reported outages at some of its North American data centers, prohibiting some customers from being able to access their data, disrupting service and even shutting down some customers' Web sites. Amazon fully restored its Elastic Compute Cloud (EC2) services within a few days. The problem was caused primarily by a network configuration change.
Despite the problems caused by the disruption to AWS's cloud services, the company maintains that it was able to throw more resources into fixing the issue than most companies operating in-house data centers. Such resources also extend to securing data against cyber theft, Singh says. "We often find that we can improve companies' security posture," he adds. "Our scale allows significantly more investment in security policing and countermeasures than almost any large company could afford themselves."
Another knock against cloud computing—and data centers in general—is that they require a tremendous amount of electricity to keep their machines running. Greenpeace is capitalizing on cloud computing hype in its own way to promote its recent report entitled "How dirty is your data?" (pdf) In it, Greenpeace calls out several companies, including all of the major cloud service companies, plus Facebook and Twitter, for their massive Internet infrastructures.
Greenpeace reports that data centers running these infrastructures consume 1.5 to 2 percent of global energy demand (3 percent in the U.S.), growing at a rate of 12 percent yearly. "If the Internet was a country, it would rank 5th for the amount of electricity usage, just below Japan and above Russia," according to Greenpeace. "But unlike geographical states, the Internet's data centres [sic] can be found all over the world, clustering in locations that offer strong tax incentives and cheap, but often dirty, electricity."
Criticism of data centers as energy hogs fails to consider that these facilities often consolidate computer operations of dozens, if not hundreds, of companies that would otherwise be managing their own IT systems as opposed to simply not using computers, cloud computing advocates counter. "One of the reasons data centers are targeted for such complaints is that you centralize so much computing they start to consume megawatts of energy," says Yahoo chief technology officer Raymie Stata. Yahoo, which owns Flickr, provides infrastructure resources for studying cloud computing. But for every megawatt used by a data center out in the open, there is probably two or three times as much energy being used by computers spread out at different companies, he says, adding that at least in a data center several computers can be consolidated onto a single server and new energy-efficient approaches to cooling those servers can be developed.