The largest manufacturer of hard drives on the planet, Seagate, has agreed to acquire online storage provider EVault for some $185 million in cash — subject to various standard closing conditions, including applicable regulatory approvals, of course. The deal is expected to close in the third quarter of Seagate’s fiscal year 2007.

EVault is a privately-held company in Emeryville, California, which offers automatic backup and data recovery services for small and medium sized businesses. It was founded in 1997 and has about 8,500 customers worldwide and a staff of about 250 people. The EVault acquisition marks Seagate’s third recent foray into online data storage and recovery: in 2005, it acquired Mirra, Inc. (a storage company that developed backup servers for individuals and businesses) and ActionFront Data Recovery Labs (which does pretty much exactly what the name suggest: pull people’s fannies out of the fire). Both those companies continue to operate as wholly-owned subsidiaries.

Seagate plans to let EVault keep doing its thing as a subsidiary, but plans to organize both EVault and ActionFront Data Recovery Las under a new Seagate Services business unit.

“Today’s announcement highlights a strategic next step into services, which is a natural extension of Seagate’s core business and will leverage our brand leadership and channel expertise to deliver solutions to the SMB market,” said Bill Watkins, Seagate CEO, in a statement. “Over the past three years, Seagate has been executing a strategy designed to broaden its customer base and increase growth opportunities by expanding beyond its core hard disc drive business into the broader storage solutions category.”

Overall, the move is seen as a way for Seagate to diversify its revenue and business model, which should please management and investors as the hard drive business is a game of constant R&D to create smaller, faster, higher-capacity drives and sell them at ever-thinner profit margins. “With Seagate Services, the Company is interested in pursuing underserved markets where it can leverage leading technology and market expertise, and provide unique value propositions to address growing customer needs,” the company said. At the same time, those drives create an ever-growing market of individuals and businesses which need to back up substantial amounts of data—and the widening availability of broadband Internet connections makes such services increasingly practical.