Disable Spotlight Indexing on a Volume in OS X

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!