I've searched both the forums and the net for a while, but have not found any information about what I'm wondering about... An external FusionDrive... Most people seem to ask about adding a thunderbolt-ssd to fuse with their internal hdd, or the other way around. But I'm looking to add a completely isolated, external FD - a 2.5" ssd and hdd. I first thought about putting a couple of ssds in an external raid case, but that would be something like $750 for 1TB (4x256GB). I then looked at the Drobo Mini, which has an m-sata slot for cacheing, but I've read it's not all too fast anyways and Drobos fileformat is hard to recover if the Drobo fails. And the Drobo Mini itself is around $600 where I live (Sweden). Then I realised I hade completely overlooked the FD that everyone is talking about because Apple manages to make a 1 or 3TB harddrive seem fast as an ssd at a lower price than pure ssd storage. So, if i get an external 2.5"/3.5" USB3.0-case and put for example a 256GB SSD and a 2TB 2.5" or 4TB 3.5" harddrive in it, could I make it into a Fusion Drive? This is mainly because I'm thinking about moving from my 2012 Mac Mini 2.6GHz with 256GB ssd + 1TB hdd to the new Mac Pro and quickly would use up the internal 256/512GB ssd that i could afford... I take a lot of pictures and need to be able to work off of the external drive, or have it as fast that is plausible to move the files to/from the drive for working with them. So its not just for storing iTunes music or word documents. Has anyone tried?