Disable Spotlight Indexing on a Volume in OS X Raw

Like a Boss
-----------

Let's say our drive is called (and mounted as) `Backup Drive`. Open up a
terminal window:

    cd "/Volumes/Backup Drive"  
    touch .metadata_never_index

Et voila!

Via System Preferences
----------------------

1. Go to **System Preferences** -> **Spotlight** -> **Privacy**
2. Drag the volume into the list
3. Ta da!