You can run "diskutil activity" and find out where all the disks actually came from. For instance I have a disk4s2 that is actually a Flash installer DMG mount

You can run "diskutil activity" and find out where all the disks actually came from. For instance I have a disk4s2 that is actually a Flash installer DMG mounted: *DiskAppeared ('disk4s2', DAVolumePath = 'file:///Volumes/Adobe%20Flash%20Player%20Installer/', DAVolumeKind = 'hfs', DAVolumeName = 'Adobe Flash Player Installer') Time=20140412-21:05:18.6399