My computer happily boots from one hard drive, although the operating system and all user data reside on another hard drive. It seems silly to have an entire hard drive taking up soace and power in the box when all I do with it is boot from it.

I'd like to make it bootable from the same drive the OS an user data are on.

How?

And if I have more hard drives (coming soon) I'd like to be able to boot from any of them.

I gather each drive I might wand to boot from has to have a working MBR and grub22 intallation.

The drive it's booting from now is MBR-partitioned; the one I want to be able to boot from is a GPT drive.

-- hendrik