"
No, don't panic I'm not trying to convert an installed setup to RAID1 by adding one disk. I want to copy the existing setup to a new 2disk RAID1 setup and make that bootable."
Aw, shucks, brain surgery on a live patient is fun!
There are two ways to do what you want:
- partition both blank drives with an identical pattern of partitions to hold each directory to mount as RAID arrays
- create a single raid array of the two whole disks and use LVM, Logical Volume Management
For a few partitions either is about the same work. If you want the ultimate in flexibility, use LVM. see
Sec 11 of Software RAID HOWTO and
LVM-HOWTO
LVM makes tinkering with disc allocation much easier as your system evolves. You should never need to re-install.
For a newbie, on a small system, the first choice is good, but you look like you may be going away from "small".
Some distros were not able to boot LVM but it has been around a while so it may work for you. LVM may cost a little performance, perhaps similar to software RAID, but it is usually unimportant.
Many installers have pretty good setups for RAID/LVM so you may find it is easier to backup/reinstall instead of reading lots of HOWTOS.
