The man in charge of Sun Microsystems' global data-center strategy and a noted speaker on data-center energy efficiency is leaving Sun to work at eBay, he said on Tuesday.

Dean Nelson, who also founded Data Center Pulse, an end-user group for data-center operators, has been made senior director in charge of eBay's global data-center strategy, he announced in a blog post.

He's the latest in a growing list of top data-center executives to switch companies.

At eBay he replaces Olivier Sanchez, who reportedly left the auction giant earlier this year to become director of global data-center operations at Apple.

Also this year, Michael Manos, the general manager of Microsoft's Data Center Services division, left the company to work for wholesale data-center provider Digital Realty Trust, and soon afterward Microsoft hired Kevin Timmons, who previously managed Yahoo's data centers.

In part, the moves reflect the growing strategic importance of data-center management at large companies. As computing equipment becomes more dense and powerful, managing data centers effectively to reduce cooling and energy costs has become more critical.

In Nelson's case, he said his "bittersweet" move was spurred by Sun's planned acquisition by Oracle.

"When the official announcement came through that Oracle intended to purchase Sun, it caused many people to rethink their future," he wrote.

"I have always believed that if I am challenged in my job, being stretched to continuously learn, have a solid team, executive support, and of course good compensation, there isn't a reason to look for something else. But with uncertainty, I also believed it was prudent to see what options were out there."

Nelson joined Sun straight from college in 1989, working as a component debugger at a factory in Milpitas, California.

He left in 2000 to work for networking startup Allegro Networks and returned to Sun after Allegro went out of business in 2003.

He spent the past few years leading a successful project to consolidate Sun's data centers worldwide, reducing its 1.4 million-square-foot data-center footprint by 41 percent. He also met frequently with Sun customers, including eBay, to understand their needs and demonstrate Sun technologies.

Nelson said eBay's Sanchez approached him about taking a job at eBay shortly before Sanchez left the auction company.

Nelson is also a frequent speaker on energy efficiency at events such as Data Center World and Datacenter Dynamics.

He called his decision to leave Sun "bittersweet" and praised the "caliber, integrity and passion" of its top executives.