how do you?

Howdy darksanity,

I'm not sure exactly what you're asking, or what you've tried.

First up, there is no such thing as "the active harddrive" on a UNIX/Linux system. There are mounted volumes and unmounted volumes, but all that matters in this context is what mount point they are on (/, /boot, /tmp, /var, /home, etc.).

There are numerous ways to make use of additional hard disk space in Linux, but the one you choose is really specific to your situation.

How about you tell us what your actual problem is, rather than the solution you've attempted, and we might be able to guide you better. e.g., something along the lines of: "My /home directory is nearly full, and I have a new hard disk that I'd like to use instead for /home. How do I move the contents of the current /home partition or directory to the new disk and mount it as /home?"

That'd be a good question. I don't know if it's your question, since you haven't identified why you need the new hard drive, where you've mounted it, or what this "folder" is for.