Western Digital, one of the last remaining big fish in the shrinking pond that is the traditional disk market, has agreed to acquire Virident Systems for $685 million. The Milpitas, California-based firm makes PCIe flash cards that eliminate network latency and provide users with faster access to their data.

Under the agreement, Virident will become a part of Western’s Digital’s HGST subsidiary. Chief executive Mike Gustafson, a 20-year industry veteran, is joining the division as a senior vice president.

Formerly a joint venture between Hitachi and IBM, HGST now supplies hard drives and SSDs to companies like hybrid storage vendor Tegile. Virident’s solutions, namely its FlashMax line and Flash Connect storage software, are expected to help the subsidiary scale SSD revenues from $2.5 billion in 2012 to $7 billion by 2017.

“The Virident acquisition is a continuation of HGST’s strategy to address customers’ rapidly changing storage needs by delivering intelligent storage devices that tightly integrate hardware and software to maximize solution performance,” commented HGST president Mike Cordano. “Virident’s server-side flash storage helps datacenter customers solve their most significant data infrastructure challenges, including application performance across diverse workloads, power efficiency, and total cost of ownership.”

It’s unclear how the acquisition will affect Virident’s partnership with Seagate, Western Digital’s biggest rival in the hard drive market. Back in January, the storage behemoth invested $40 million in Virident as part of a milestone strategic partnership that gave the latter access to its channel.  But so far, the deal is a big perk for Western Digital.

“This is a great win for Western Digital and an exit for Virident shareholders.  Interesting is the Seagate investment and the status of the OEM deal,” says our own John Furrier, CEO of SiliconANGLE, in reference to the $40 million investment mentioned above.  “The move opens Seagate’s OEM and distribution channels to Virident’s FlashMAX cards and broadens Seagate’s solid state portfolio beyond its SAS-interface Pulsar drives.”

Western Digital’s latest flash investment comes on the heels of Fusion-io’s push into the open source community. The SSD giant decided to make its Atomic Writes API available for developers, along with a flash-aware Demand Paging Extension and a key-value interface called NVMKV.