Apple says the feature is available exclusively with Late 2012 hardware
Mac developer Patrick Stein has discovered that you don’t need a brand new Mac to use Fusion Drive, a new feature that automatically and dynamically moves frequently used files to Flash storage for quicker access.Stein discloses his findings on his tumblr blog, noting that “Since Apple has announced the Fusion drive, people have wondered if it’s possible to use the fusion drive on older machines with a SSD and HDD.” The answer? Yes.
Apple says “Fusion Drive is a new storage option for Mac mini (Late 2012) and iMac (Late 2012) computers that combines the performance of Flash storage with the capacity of a hard drive.”
But Stein used some Terminal magic (and fiddled with some cables) and managed to configure an internal solid-state drive (SSD) and a traditional hard disk drive (HDD) attached via USB on Mac Pro to combine them into a single volume that Fusion Drive could recognize.
The SSD he used is an old Vertex2, “so nothing Apple specific,” Stein says. Also, he managed to get Fusion Drive happening on a standard OS X 10.8.2 installation.
He also confirms that mounting the drive with “-o noatime” doesn’t change the caching behavior.
“Presented as a single volume on your Mac, Fusion Drive automatically and dynamically moves frequently used files to Flash storage for quicker access, while infrequently used items move to the hard disk,” according to Apple.
“As a result you'll enjoy shorter startup times, and as the system learns how you work you'll see faster application launches and quicker file access. Fusion Drive manages all this automatically in the background.”
The feature was introduced on October 23 during Apple’s iPad mini event which also witnessed the introduction of three new Macintosh models – two upgraded, one brand new.