As I say, I have no experience with internal data drives, so probably can't help you from there. However, I'm assuming that there is a "device" to represent them in the devices tree and that is what you found. If so, hopefully the devices are DCE devices in which case there is a good chance that there is a log file for the activity. If you open the device data there should be a device number, say 40. You can then look in /var/log/pluto/40_<devicename> for its log messages when it goes off line... Failing that, I would assume you need to look at the internal Linux autofs or ntfs(-3g?) modules for their logs....