Rescanning a usb-mounted fs causes scsi device address to change

Hello all!

This is my first post to the list so let me appologise if I am
missing something obvious.

I am writting a perl program that backs up data to a USB2/Firewire
connected hard drives. I've been writting it under Fedora Core 1 and 2 and I use Kurt Garloff's 'rescan SCSI bus' script. What I have found is that if a usb-connected partition (say at '/dev/sda1') is mounted and the rescan script is run (via 'sudo' with the '-r' remove switch) the device shifts to '/dev/sdb1' instead of being ignored. This obviously breaks any mounts and associated bad stuff (tm) happens.

I am an amature programmer so again I worry that I am missing
something obvious. I've been reading as much as I can on the 'scsi add|remove-single-device w x y z > /proc/scsi/scsi' call but there seems to be very little documentation on how these calls work. If someone doesn't know what's happening but can point me at something that might help be figure this out that would be greatly appreciated, too.

In case it helps, I am currently developing this on an IBM thinkpad
a22m (Intel 440BX/P3 1GHz) machine with an ALI USB2/Firewire PCMCIA card and an external USB2->IDE carrier that uses removable 3.5" IDE trays (poor person's hot-swap). If any other info/specs will help I'll be glad to pass them along.

Thank you in advance!

Madison