I've got a USB hard drive (Intenso 320GB 2.5") which is plugged into my Pi. It auto-mounts to /media/pi/ but I umount it from there and manually mount it to a folder /mnt/recordings where it is used as the destination for TV recordings made by TVheadend.
I've noticed that at random times (not related to movement of the USB connection between drive and the Pi), the drive disconnects itself. The first I know is when I see a pop-up dialogue "Removable media is inserted - Open in File Manager". It remounts to /media/pi/ - always the same ID. However I notice that the raw device /dev/sda and sda1 changes to /dev/sdb(1) and then sdc(1), and so on for each successive disconnection and reconnection.
I was going to reconfigure TVheadend to refer to the /media/pi/ mount point, but there's something that prevents TVHeadend working in this case, even though I can "ls" the files on the drive and the mount point has 777 permissions.
Any suggestions? The drive is formatted as NTFS. Could that be relevant: does NTFS have some sort of auto-dismount capability.
I'm about to try another drive to see if that fails in the same way. I didn't notice a memory stick (formatted as exFAT) fail in this way, even though it appears as the same raw device /dev/sda(1).
The drive has been used for ages on various Windows PCs without any signs of auto-dismounting.