You can use blktrace to see who is accessing the drive. My first suspect would be udisksd so you might try killing that process and see if that makes it go away.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1733068 Title: Unmounted USB drives wake up on 16.04 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+bug/1733068/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
