Couldn't get Diskwarrior 4.4 to boot up my 2012 mini. Ended up connecting my OWC external drive( Target Disk Mode) to an old Mac Book, then running DW 4.4 to rebuild directory on (OSX10.8.2) OWC Drive. Then attached the OWC to my mini, booted up from the OWC drive, partially installed the DW 4.4 in utilities folder of it, then was able to rebuild directory on mini's 256 Gig SS drive.