I am used to the fact that a Linux installer honours a pre-existing install of Windows and offers to setup the computer with a dual-boot option during installation. Vice-versa no Windows installer honours any other pre-exisiting OS. Therefore I was surprised that when I tried to install Ubuntu 16.04 on my PFSense box (FreeBSD), the Ubuntu installer did not even see that a BSD install exists on the drive. I chose the "erase all" option, but when I rebooted after the installer has finished, the system went straight into PFSense without giving me any option to select Ubuntu.
I myself have been using the backup software BackupPC for almost a decade, and I started to backup our lab computers to a central backup server about two years ago. BackupPC supports deduplication and therefore much data can be stored on a couple of 2 TB drives.