Last week the people from Apple presented Fusion Drive, an interesting system that uses SSDs and HDDs in a kind of matrix that improves the user experience of OS X Mountain Lion. Apple said that this system is only available on iMac 2012 and Mac Mini 2012, but a developer managed to activate it on a Mac Pro as well. His computer runs OS X Mountain Lion 10.8.2, an SSD and a 750 GB HDD were used, and everything worked in both HFS+ and ZFS format.
Attached are a 120GB SSD (disk1) and a 750GB HDD (disk7) to my Mac. I attached the SSD via SATA to be sure that the system could figure out that it's an SSD via SMART. The HDD is attached via USB. USB I chose to clearly see a difference in speed.
On his blog the developer describes the whole procedure for activating Fusion Drive on Macs other than those officially supported, but you have to remember that everything only works between a Mac and an SSD. Basically, the system uses the SSD as a kind of cache for the files on the HDD, allowing you to open them much faster than on the classic HDD.
