Rebuilding a Fusion drive when all else is hopeless

README.md

Today, a poorly-timed tick of the "enable FileVault" box on El Capitan (OS X 10.11.1) resulted in a very dead hard drive that Disk Utility was unable to repair. Here's the basic command-line solution:

Show your CoreStorage volumes:

diskutil cs list

Delete CoreStorage logical volumes:

diskutil cs deleteVolume UUID

Delete other CoreStorage volumes (groups):

diskutil cs delete UUID

When you have no more CoreStorage stuff, list your normal volumes:

diskutil list

Make a combined partition from your SSD (e.g. disk0s2) and your HDD (e.g. disk1s2), making sure they're in the right order:

diskutil cs create 'Macintosh HD' disk0s2 disk1s2

You'll be given the new logical volume's UUID. Use it to make a new volume:

diskutil cs CreateVolume [UUID] jhfs+ 'Macintosh HD' 100%

Bueno.