System I'm working on has a terabyte partitioned somewhere between 300-335 gigs each.  I remember hearing a while back that each drive no matter what size should have at least 10% free space, or was it 30% or 20%?  10% seems reasonable to keep free but I wanted to double check.

Thanks in advance for the help!

On stand-alone storage (non-Unity) 10% might be a little high.  You really only need enough room for the media databases to modify.  In that case, a couple GB's would work.  On Unity systems, 10% is more reasonable, as you also need room to Synchronize & Optimize.

BTW ... when I first heard 10%, in 1994, drives were only 2GB ... so yeah, it made sense.