I have a late 2012 27" iMac with an official 3tb Fusion drive inside. Recently the HD failed & it was sent into an Apple service centre which replaced the 3TB drive, but forgot to 're-bond' the 2 parts of the fusion drive together. The Apple service centre have said they'd fix it & re-bond the 2 drives together to make the Fusion Drive however I'd need to make 2 round trips of 100 miles & leave it with them for a few days + I'm really busy with work & can't spare the machine for that long (its currently running fine on only the Spinning HD). Does anyone know the CORRECT way to re-bond the 2 HD's under the latest build of Yosemite (apparently the 'old' core storage method stated on the interwebs no longer works), or should I just take the hit, lose a few days of work & a lot of Deisel & get them to fix it???? Thanks Guys!