How can I prevent Ubuntu from mounting particular partitions/devices?

Solution 1:

The solution is to add them to /etc/fstab, but with options to prevent them from being automatically mounted. The option you want is noauto rather than auto. For example, to prevent a windows partition from being mounted, you could add an entry like the following:

UUID=C2A281E4A281DCF3 /media ntfs-3g defaults,noauto 0 0

You can run blkid to retrieve the partition UUID:

sudo blkid

See "Using UUID" in the Ubuntu Docs.

Or, to make it more self-documenting and simpler, although not quite as fail-proof, I have switched to using disk labels rather than UUIDs. You just need to make sure the label is descriptive and unique; unlike using UUIDs, labels are not guaranteed to be unique, but I've never run into a problem, and it's more convenient, as you can swap a different partition by using the same label, and no need to modify /etc/fstab, or to run blkid.

Contrast the above entry with this one:

LABEL=Win_sys   /media     ntfs-3g   defaults,noauto   0  0

A good explanation of fstab options can be found on the ArchWiki and on the Ubuntu Docs.

Solution 2:

Just use gnome-disks facility in Ubuntu. Type this in your terminal:-

user@user-X550LD:~$ gnome-disks

Easy to use. Click on any partition and select the "settings" cog wheel down at the bottom near the "play" and "minus" signs. Select mount options and voila.