Setting Up Your Own High Performance 'Fusion' Drive
Step by step how-to in setting up your own Apple Fusion drive., which is smart about locating frequently used portions of files on the fast SSD.
I used an OWC Mercury Accelsior 480GB PCIe SSD along with a 2TB hard drive for a 2.48TB logical volume.
The 'fused' volume below is really a 480GB PCIe SSD and a 2TB hard drive!