Why doesn't FileVault work on a RAID?

[Julien]

I have a RAID and Turn On FileValt is grayed out. I have seen threads and posts saying it doesn't work with a RAID. Is there a technical reason it doesn't or can't work (files being divided over disks?)? Or is this just an Apple implementation that needs to be address?

 

[ginkaninka]

I think this could be because Apple want you to use Core Storage instead. This supports RAID-like spanning of disk with encryption.

In the Terminal, check the man page for 'diskutil' and read the section regarding Core Storage near the end.