I've been trying to find information on how to upgrade the original SSD that came with my mid-2011 iMac. I ordered the machine with both an SSD and a spinning hard disk (250GB + 1TB), but the SSD has always been on the hairy edge of being full, especially with part of it partitioned off to run a Windows virtual machine in Parallels. Everything I find when I search for information about how to upgrade the SSD talks only about replacing a HD with an SSD, or adding an SSD to a machine with only an original HD. Nothing about how to replace the factory SSD. Can anyone tell me what kind of SSD Apple actually put in these machines, and if they are user upgradeable? Links? Thanks much.