Mesosphere has raised a $36 million Series B round, led by Khosla Ventures, to commercialize a data center operating system (DCOS) that lets applications run on pools of physical and virtual machines.

The DCOS takes the focus away from individual machines, in other words. Applications get automatically provisioned onto unspecified resources available in public or private clouds. We've seen data center resources such as computing and storage get turned into anonymous pools; now the entire data center is getting that treatment.

You can count San Francisco-based Mesosphere as part of the rapidly expanding universe of open source tools and DevOps for the data center. The company was founded in 2013 to commercialize Apache Mesos, a distributed systems kernel built for that trick of liquefying the data center into one pool.

Mesos is open source software that was developed at the University of California at Berkeley and has attracted some notable users including Airbnb, Netflix, and Twitter. It runs on every machine in the data center, talking to applications via APIs. To keep resources isolated between users, Mesos takes advantage of control groups (cgroups) in Linux.

Investors apparently believe in the concept, given that Mesosphere not only raised more money quickly (a $10.5 million series A was announced in June, following $2.25 million in seed funding) but also attracted Khosla, a blue-ribbon venture capital firm led by Vinod Khosla, a founder of Sun Microsystems.

Mesosphere employs 40 and expects to grow to 120 in 2015, according to press reports today.

Other companies participating in the Series B round included Andreessen Horowitz and Fuel Capital — both of which contributed to Series A — and SV Angel.