When I plug in an external drive, Spotlight starts to index it automatically. I almost never want this to happen. Please provide a preference that allows me to turn off automatic indexing of external drives. This is a constant problem for me, because I have many external drives that I use for various purposes such as backup, and I don't want Spotlight to index them or put hidden directories on them or modify them in any way. For example, I'll often have a clone of some volume on an external drive, and I don't want Spotlight to index the clone.