I have a file sharing website, and my files hosted in a server with those system specifications:

32GB RAM
12x3TB
2x Intel Quad Core E5620

I have files in this server up to 4gb for each file. 446gb is full (/36TB)

[root@hosted-by ~]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda2              50G  2.7G   44G   6% /
tmpfs                  16G     0   16G   0% /dev/shm
/dev/sda1              97M   57M   36M  62% /boot
/dev/mapper/VolGroup01-LogVol00
                       33T  494G   33T   2% /home

And take a look at this:

Why is the wa% so high? (I think that what makes the server to be so slow)