Nasuni, a provider of software that streamlines data transfer to cloud storage outlets, announced today that it has raised $15 million in its second round of funding led by Flybridge Capital Partners.

The company’s software serves as a link between local storage and any number of cloud storage providers, which store data in remote servers and usually charge per gigabyte of storage, like Iron Mountain and Amazon’s S3 storage service. The software behaves like a virtual server that hosts some data locally in a cache and regularly transfers data back and forth between cloud storage providers.

It can be slower and sometimes less efficient to use cloud storage, though. Nasuni’s software attempts to remove some of the headaches by including a number of functions that speed up data transfer. One example is de-duplication, which only transmits changes in files to the cloud server rather than the whole file if it’s already present on a cloud server.

There’s been a lot of interest in moving data to remote cloud servers because it can cut costs for many companies. Services like Nasuni’s let companies add storage as they need it. That means they don’t have to install and maintain expensive in-house databases that are often underused. Cloud-based service provider Salesforce recently launched its own version of a cloud-based database called

The company was founded by storage industry veterans Andres Rodriguez and Robert Mason in 2009 and has 25 employees. Rodriguez and Mason have already seen some success in cloud storage, selling their earlier company Archivas to Hitachi Data Systems in 2007 for $120 million. Nasuni raised $8 million in a first round in March, 2009, from Sigma Venture Partners and North Bridge Venture Partners.

[Photo: Tom Raftery]