VMware has acquired cloud-based storage and back up service Mozy from its parent company EMC in order to get first hand experience of operating a public cloud system.

“We believe that, by being directly engaged with the delivery of such a service, VMware will further ramp our own cloud-related learning and accelerate new IP, scale and capabilities into the products that we provide to our customers and public cloud partners,” wrote chief technology officer Steve Herrod on the virtualisation software company’s official blog.

Herrod wrote that Mozy has 1 million customers, including 70,000 businesses, and stores more than 70 petabytes of data in its various data centres.

Mozy’s chief operating officer said it will continue to invest in it technology and services, but that the companies will “integrate longer-term development plans central to building and delivering hybrid cloud solutions”.

Launched in 2007, Mozy originally offered paying customers unlimited storage, but introduced a tiered payment plan earlier this year. Some customers reacted angrily to the change.

Meanwhile, rival cloud-based storage company Dropbox has overtaken Mozy in customer numbers, reaching the 4 million users in January 2010.

It is not the first time VMware has bought into a cloud provider. In 2009, it acquired a $20 million stake in Terremark, a cloud-hosting company that has since been acquired by US telco Verizon Business.