1. Login to HELM control panel.
2. Click on Domains. You will see your domain listed on the page. Click on it.
3. You will see all the menu options listed and one of them is "Advance Domain Options". Click on the "Advance Domain Options" icon.
4. Click on the "Disk Space Usage" icon.
5. The page will shows up the disk usage for your MYSQL, MS SQL database ( including the transaction log file ).
As a side note, the disk space shown is only updated once per day, so any latest changes may not be reflected in this total. You may get the latest result by clicking on the "Recalculate Disk Space " hyperlink.