Comment 18 for bug 105623

Suggested fix:

Add a debconf setting to enable/disable the automatic activation of the lvm volumes, and leave it disabled on the cd. That way you can have the udev rules in there, but they will only allow the devices created by libdevmapper to show up, not detect and activate volumes found on physical disks. This would also allow you to pass the debconf setting as a kernel boot parameter to force it on or off at boot time.