I'm adding 4 HD's to my new server build (ubuntu 12.10) and the sys drive is listed as /dev/sdb. I wasn't able to find in the mobo manuals which sata port is first in line. The machine boots up ok, but I was unsure if the order (/dev/sda, /dev/sdb) makes a difference.
thanks.
It does not.
Also for your purposes Linux now prefers the use of UUID's for mounting disks:
This way you specify a UUID of what the exact disk is. By default Ubuntu will mount disks it sees during installation via this method. If you have a machine with multiple disks then you should consider doing it this way.
So instead of trying to guess which disk is on which port and all that, you just define the exact disk. For example in the old days if you took disks out of a server and put them back in the wrong order, it wouldn't boot if the disks got reassigned different letters, using UUIDs fixes that.