Oracle’s new best friend Mellanox Technologies said Monday that it’s buying sometime rival Voltaire for $8.75 a share, which works out to $218 million cash, roughly a 36% premium.

Less what Voltaire’s got in the bank, it’s going for $176 million.

Oracle recently bought 10.2% of Mellanox; it uses Mellanox’ InfiniBand widgetry in its servers, including its precious Exadata appliance.

Mellanox was one of the many exhibitors at 7th Cloud Expo in Silicon Valley in Nov 2010

Terms of that particular transaction weren’t announced. Oracle’s money will help Mellanex buy Voltaire. Oracle did say the investment was meant “solidify a common interest in the future of InfiniBand,” and until Voltaire branched out recently into 10 Gigabit Ethernet switches it was a pure InfiniBand play. Now Mellanox can use Voltaire as a springboard into Ethernet.

The deal should close in Q1 and create a 700-man combination worth at least $217 million a year, judging from what the two companies did in the 12 months ending September 30. Mellanox contributed $149.5 million to that number and Voltaire lost $4 million during that time, which may explain its motivation.

Mellanox, which makes adapters and InfiniBand chips as well as switches, said the acquisition would give it added scale and “permit it to operate as a larger, more successful and more profitable enterprise.”

“Together, we believe the combined company will be a stronger business partner and system solutions provider, delivering customers a comprehensive range of end-to-end connectivity solutions,” Mellanox CEO Eyal Waldman said in a statement.

Mellanox said it means to keep all product lines “to ensure continuity” for customers and converge them down the road in future generations obviously to save money. Voltaire uses Mellanox chips in its switches.

Mellanox spoke of running the combined companies under a unified management team and keeping the offices both companies have in Israel, the US and elsewhere.

Voltaire CEO Ronnie Kenneth is supposed to join the Mellanox board next May.

Mellanox figures Voltaire’s business, despite its losses, should add somewhere between two cents and a nickel (non-GAAP) if not more to its earnings in fiscal 2011. It also figures it should find cost synergies of $10 million a year by the end of 2012.

• Mellanox InfiniBand Adapters Provide Storage Virtualization Connectivity to Galactic Computing's VSTOR
• Mellanox Demand Increases VMware Virtualization Environments
• Mellanox Enters Ethernet Market
• Mellanox and Novell Drive High Bandwidth Virtualization Into Data Centers