When MegaUpload got shut down early last year, the fate of millions of files stored in the cloud fell into limbo. A large number of those files met their digital demise earlier this year when Danish web hosting company LeaseWeb wiped the MegaUpload servers they had been operating.

Kim Dotcom was angry at the time but perhaps even more upset were the people that used the service to store legitimate, “innocent” files in the cloud. According to the latest data from researchers at Boston’s Northeastern University, an estimated 10 million innocent files were among those deleted by LeaseWeb.

The researchers ran a study to check the copyright infringement status of files that were uploaded just before the takedown in January 2012. Specifically, they looked at metadata from links to content that had been hosted on the site and took representative samples from a thousand files at a time. From here, they manually decided if the files fit into one of three categories: infringing, non-infringing or undecided.

They ultimately discovered that 31 percent of content on Megaupload was infringing but perhaps more importantly, at least four percent of the 250 million uploads – or around 10 million files – were clearly original content. Furthermore, researchers were unable to determine the nature of 65 percent of files uploaded which means many of those could have also been original content created by users and not copyrighted material.

If nothing else, the whole fiasco should instill the importance of having multiple backups of important data in multiple locations.