I just purchased a 6 month old iMac and found the previous user/seller has done something goofy with the formatting of the Fusion drive. Now there are two volumes on the desktop and in Disk Utility. The SSD and HDD. I'd like to restore it to the factory setup. (One volume for everything SSD+HDD combined) There's no worry about backing up anything the machine is blank. Unfortunately all recovery modes/Disk Utility don't see the problem - DU doesn't think it needs fixing! But at the same time I'm wondering what's the difference? Why not just put programs on the SSD and data on the HDD? It would be a PITA for backups though. Any ideas how to easily re-pair the SSD and HDD back up again as it was shipped? This is a late 2015 Retina iMac and from what I've read El Capitan (default OSX) had removed the Fusion pairing function out of Disk Utility.