Hi Sam, It doesn't matter what your devices are called. In fact you are best advised to avoid use of the /dev/sd* names where possible as these names may change for reasons other than drives being hotplugged. For example if your storage controller needs a module to detect drives, then order of module loading may affect device naming.
Try to use the paths in /dev/disk/by-id/ or similar. mdadm itself recognises array component devices by its own metadata so does not care what they are called (as long as you haven't told mdadm to ignore those device names). The only thing you might want to check out is whether your BIOS is going to see a bootloader on the drive it tries to boot from next time. Cheers, Andy -- https://bitfolk.com/ -- No-nonsense VPS hosting