server Disk Usage fix

I need someone with WHM/C panel experience to help with ongoing issue diskcritical running low Percentage Full: 93% /dev/root 49G (size) 3.5G (Available) For some reason this partition keeps getting full pretty quickly. I have other disk space available on /dev/md3 1.6T (Available) I have a video based website running off of Wordpress. I upload videos directly to server. I would like my website/ videos files that are being uploaded daily to be allocated to /dev/md3 1.6T partition which has the most space on my server. I would also like /dev/root partition cleaned/minimized so that the disk space does not reach 99% full and crash my website.