Just weeks after we reported a shift in strategy at VMware, the virtualization giant has announced its intent to acquire Virsto Software, a provider of storage performance optimization software.

VMware is refocussing its efforts to what it knows best: infrastructure. The company had intended to branch out to provide products at every layer of the entire software stack, including cloud-based applications. But with competition from scrappy startups and legacy vendors, VMware is concentrating its energies on the virtualized data center.

John Gilmartin, vice president of VMware’s storage and availability unit, said the company intends to extend the “benefits of virtualization to every domain of the datacenter — compute, network, and storage.” VMware has made a number of strategic acquisitions to bolster its technology in each of these domains, including the high-profile purchase of Nicira for $1.26 billion.

The buy-up, which the company announced in a blog post today, is expected to close at the end of the quarter. The terms of the deal were not disclosed.

The Sunnyvale, Calif.-based Virsto has raised over $24 million in venture capital from investors, including August Capital, Canaan Partners, Interwest Partners, Southern Cross Venture Partners and Correlation Ventures.