How to Disable Drive Auto Mounting

I have been searching around here and online but can't find an answer (maybe because it is late and I am not thinking straight about what words to use) so I thought I would ask here.

I have an external drive that contains 2 partitions. When I start the computer or plug in the external drive both partitions auto mount onto the desktop. Is there a way to disable this? Preferably for only one of the two partitions.

If you care why I am doing this, one partion (the one I want to auto mount as normal) is for TimeMachine. The second partition (the one I do NOT want to auto mount) is simply for utility/extra storage that I would like mount via Disk Utility only when I need it.

Thanks for any suggestions.

 

doobs, Thanks for the reply and suggestion. The main reason I didn't want it to auto mount is to reduce the amount of potential confusion my wife (who isn't the most savy) may have. Not to mention trying to keep the desktop clean. Between the internal HD, iDisk, these 2 partitions and the storage on my airport extreme there are a lot of friggin' drives.

But you bring up a good point in that I don't think I mind if the second partition is mounted as long as it is hidden (shouldn't use too much resources sitting there idle). How do I hide a single drive in the Finder? If it is obvious I am sorry, maybe I can use the "late" excuse again?, but I can only see where you can exclude ALL external drives.

Thanks again.