Cloud computing can cut the cost of running small workloads though may actually be more expensive for larger compute jobs, compared to the costs of running such work in-house, according to researchers from Pennsylvania State University.
Researcher Byung Chul presented these findings at the Usenix HotCloud 2011 Workshop on Hot Topics in Cloud Computing, held this week in Portland, Oregon.
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Chul, along with Bhuvan Urgaonkar and Anand Sivasubramaniam, analyzed the costs of cloud computing in the paper, "To Move or Not to Move: The Economics of Cloud Computing," which was submitted to the conference.
"Many people expect cost savings compared to traditional hosting for the reasons of the pay-as-you go nature of the cloud, or its elasticity. But there is no consensus about whether the cloud really provides the economic benefits or not," Chul said. "The goal of our study [was] to systemically investigate what conditions or variables affect the costs in what ways," Chul said.
Purveyors of cloud services like to tout that moving workloads to the cloud can save organizations a lot of money. At the very least it eliminates the capital expenditures needed for equipment and software. And cloud services also, in theory, can run equipment more efficiently, and hence less expensively, than organizations themselves can.
The benefits are not quite so obvious, the researchers argued. Cloud savings depend on many factors, such as the workload intensity, how much the application will be used in the years to come, how much storage is needed and the software licensing costs.
For the study, the researchers constructed two sample multitier workloads, based on the Transaction Processing Performance Council's TPC-W benchmark, which emulates the workload of an online book store, and TPC-E benchmark, which emulates online transaction processing in a brokerage firm.
The researchers then calculated out the costs of running these workloads over a 10-year time period, either in-house, in an Amazon EC2 (Elastic Cloud Compute) or Microsoft Azure hosted cloud service, or as a combination of in-house and these cloud services, called a "hybrid cloud."
"Overall, we find that in-house provisioning is cost-effective for medium to large workloads, whereas cloud-based options suit small workloads," the paper said.
Small workloads were defined as those with 20 transactions per second, with a growth rate of about 20 percent per year. Such workloads would cost about $10,000 a year to execute in-house, while costing only $1,000 a year in a cloud. Over the period of 10 years, however, the costs of the two choices may even out, thanks to the 20 percent growth rate of the workload.
The tests assumed that hardware and software would be refreshed every four years. Thanks to Moore's Law, the new hardware would have improved performance, which could help keep costs down for in-house implementations. Cloud computing pricing, on the other hand, may not reflect the lower costs enjoyed by the newer hardware, the researchers observed.