Cpanel/WHM allows to use folders other than /home for creating cpanel account.
If you run out of disk space in a cpanel server, you can add a new hard drive, format and mount it as /home2
Once this is done, you have two options to tell cpanel to utilize /home2.
1. Edit /etc/wwwacct.conf and set HOMEDIR as /home2. All new accounts will be created in /home2 from now.
2. Edit /etc/wwwacct.conf and set HOMEMATCH as /home*. All new accounts will be created in /home or /home2 depending upon the amount of free space in /home or /home2