How to split up a Fusion Drive
Apple's Fusion Drive combines a fast solid state drive with a slow, platter-based hard drive to deliver both speed and capacity. It does this well, considering it requires no interaction from the user.
However, you may want to separate a Fusion Drive, either to gain a greater level of control or to simply swap out one of the drives. Whatever your reasons are, separating a Fusion Drive is a fairly simple process.
Backup your data
Splitting up a Fusion Drive will erase any data contained on it. if you want to preserve any data, back up first. You can check out our guide to backing up with Time Machine or our more general guide if you don't need to save everything.
Bust open the terminal
If the two drives you want to separate aren't currently running the OS but are attached to your computer, you can just open Terminal (Applications > Utilities > Terminal). Perhaps you created a Fusion Drive with a pair of external drives, or you have a Mac Pro, which has multiple drive bays, and you've paired a couple of drives in the bays as a Fusion Drive (but aren't used as a boot drive).
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