How to move the Downloads folder (in Mountain Lion) to another disc

Solution 1:

It is possible to do this from within the Terminal. Launch it from Applications → Utilities → Terminal.

1. Move the Downloads folder to your second drive, replacing Data (the name of my second drive) with whatever yours is called. You may be prompted for your OS X password.

   sudo mv ~/Downloads /Volumes/Data/Downloads
   

2. (Optional) Create a symlink to allow you to access your new Downloads folder in the old location. Again, replace Data with the name of your second drive.

   ln -s /Volumes/Data/Downloads ~/Downloads
   

This has just worked for me on OS X 10.8.1.

Solution 2:

I'd encourage you not to mess with permissions.

You can create a new folder on the other drive (or use any other folder that you prefer) and use Safari preferences to set the new folder as the destination for downloaded files to be placed.