How to disable mediascanner-service?
To disable for all sessions:
sudo sh -c "echo manual >> /usr/share/upstart/sessions/mediascanner-2.0.conf"
To disable for your user only:
echo manual >> ~/.config/upstart/mediascanner-2.0.override
If you are sure you will not miss the "service" of mediascanner :o), just remove/purge it from installed packages:
sudo apt-get purge mediascanner2.0
And you can also purge the libmediascanner:
sudo apt-get purge mediascanner2.0 libmediascanner-2.0-0
libmediascanner comes together with mediascanner2 in Ubuntu update. It is the Access library for the mediascanner's index