ClearSky Data, a startup with a cloud service for storing companies’ data in various tiers based on customers’ needs, is announcing today a $27 million round of funding, with content distribution network Akamai participating.

ClearSky Data’s service keeps companies’ primary, important data offsite in block storage on hardware that the startup maintains. ClearSky sticks less frequently accessed data in a public cloud — specifically with the Amazon Web Services S3 object storage service.

“We’re figuring out on an ongoing basis using our own algorithms which of the data within the workload are actually hot and warm and cold, and making sure that data is sitting where it needs to be sitting in our service,” cofounder and chief executive Ellen Rubin told VentureBeat in an interview.

Because it provides a cloud service, ClearSky Data could be mistaken for a competitor to existing public cloud storage services available from Google and Microsoft, as well as Amazon S3. Not so, said Rubin. The real competitors, she said, are enterprise-focused storage vendors like EMC and NetApp. That’s bold and hopeful, but perhaps will prove to be true, at least to some degree, if the startup can persuade several big companies to try its service. It helps that there aren’t a ton of companies doing what ClearSky Data is doing.

ClearSky Data calls itself a “global storage network.” That’s misleading, as the startup only maintains hardware to provide its service in three U.S locations — Boston, Las Vegas, and Philadelphia. ClearSky will set up more facilities in the future, and part of the new money will finance that, Rubin said.

ClearSky Data started in 2014 and is based in Boston. Around 40 people currently work for the startup.

To date, ClearSky Data has raised $39 million. Polaris Partners led the new round.

Akamai has previously invested in cloud security startup FireLayers, security startup Rubicon Labs, and networking startup Saguna.

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