There's a maxim in the data center business that you can't manage what you can't measure, and eBay has come up with the mother of all measurement systems for calculating data center efficiency.
The online auction giant has devised a methodology that looks at the cost of its IT operations in dollars, kilowatt hours and carbon emissions, and ties those costs back to a single performance metric -- in eBay's case, the number of buy and sell transactions its customers make at eBay.com.
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The result is a set of data that provides the equivalent of a "miles per gallon" metric for data centers, which organizations can use as a baseline to improve on over time, said Dean Nelson, head of eBay's Global Foundation Services, which manages its data centers worldwide.
"EBay is a single system, it's the sum of a million parts, and we needed a way to measure and convey the efficiency of this system," he said Tuesday at the Green Grid Forum, a data center efficiency conference in Santa Clara, California.
EBay has published the methodology in the hope that other companies will adopt it too, much as the industry rallied around Power Usage Effectiveness, or PUE, as a general metric for data center efficiency.
EBay's system, which it calls the Digital Service Efficiency (DSE) dashboard, goes further than PUE, measuring its IT infrastructure and relating it to the four metrics its top executives care about most -- revenue, performance, environmental impact and cost.
In the process of sharing its method, eBay took the unusual step of releasing a wealth of data about its own data centers. It operated 52,075 physical servers at the end of last year, and generated 740 metric tons of carbon per million users, or 1.6 tons per server.
It set itself a target of reducing its cost per transaction and carbon emissions per transaction by 10 percent this year, and of increasing its transactions per kilowatt hour by the same amount, Nelson said. It shared those figures too -- apart from the costs in dollar terms, which it views as competitive data.
"We're not going to show our detailed profit and loss numbers to everyone; we're devising a metric to show how much we're improving efficiency each year," said Rohini Jain, finance lead for eBay's technology infrastructure.
Still, it's more data than most other companies provide. For instance, Google doesn't disclose how many servers it operates or how much power its data centers consume, though it does publish efficiency data.
It may not be easy for other companies to replicate eBay's methodology. EBay has a straightforward metric against which to measure performance -- the number of transactions its customers make, which it measures in URLs -- while many other firms have more complex business models.