my hardware is of a ReadyNAS 4200 V2 Since DSM 6 I've been having issues, took the plunge and did DSM 7 all is good and everything is working. I started with 1 drive in the first slot, it appears that between 1-4 there's no issue with the drive # assignment but drives 5-12 the number appears to be randomly assigned.
The first drive that is inserted in slot 5 and above automatically gets drive 7 regardless of which slot I put it in. At the moment, there's nothing on the NAS yet so I'd really like to get this sorted out, with 12 drives and something fail, it will be a nighmare to identify it which leads me to the next issue. when I go to locate drive, the amber light doesn't flash.
FWIW, my MB have a total of 6 ports and only 4 are being routed to the front bays.