SwiftStack, a startup that has built object-storage software based on the Swift object-storage portion of OpenStack’s open-source cloud software, is announcing today a $16 million funding round, following on months of renewed interest in OpenStack.

The startup has already attracted 40 customers, including eBay, HP, Pac-12 Networks, and Time Warner Cable. The new cash will help SwiftStack push its software into more companies’ data centers, founder and chief executive Joe Arnold told VentureBeat in an interview.

And even though big technology vendors Cisco and EMC have made prominent acquisitions of OpenStack startups in recent weeks, and even though VMware announced its own OpenStack distribution, and even though HP has articulated major interest in dominating OpenStack, SwiftStack intends to stay private, thank you very much.

“We’re going to build a great company,” Arnold said. “We truly believe that, and that’s what were setting out to go do.”

SwiftStack faces competition from publicly traded Red Hat, which bought InkTank earlier this year and in doing so entered the open-source object-storage market. InkTank sells an enterprise version of the Ceph open-source storage software.

At the same time, other startups, like Scality, offer scalable storage software that companies can run on their own hardware instead of going to specialty storage vendors like EMC and NetApp.

“Storage being bought as open source-commodity hardware is a fairly new thing for people buying storage, and that’s the hump that we’re getting people over to buy this type of solution,” Arnold said.

In addition to selling software to run in companies’ data centers, SwiftStack provides a Web interface for managing storage with the latest edition of the startup’s software.

Forty people work for San Francisco-based SwiftStack now. “We’ll easily double that by this time next year,” Arnold said.

SwiftStack started in 2011. To date it has raised $23.6 million. OpenView Venture Partners led the new round. Mayfield Fund, Storm Ventures, and UMC Capital also participated.