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.

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