How does CAM determine the order to number drives ?

[Pete French]

Hi, I have a small server which boots from an
Adaptec 2940 controller under CAM, and serves drives
off a Compaq 4200 RAID controller.

I have spent the afternoon ttrying to upgrade the
RAID controller from a 4200 to a 5300. The 5300 uses
the CISS driver rather than the IDA driver, and this
lives under CAM too. Thus my RAID drives have changed
from being idad devices to being da devices.

Unfortunately the RAID controller gets scanned first
so I now have a da0 and a da1 where I didnt before, and my
root drive has moved to da2.

I can't persuade it to boot like this - it refuses to mount
the root from da2. The simplest solution, of course, would
be to somehow force the CAM system to scan the Adaptec
controller first, so that the root device is back in da0
where it belongs. But I cant find out if there is a way
of dojing this, or indeed how the system determines the order
at all.

Any suggestions ?

-pcf.

PS: System is 4.10-RELEASE, though I suspect this is irrelevent