Root folder is full but no files there

[harisms]

hi, i'm using sentora panel for a month. today i faced a problem which i cant able to connect with database so i check my storage which is full. so i deleted some files i uploaded to root folder and the problem solved.

my phpsysinfo image 
   
http://imgur.com/zrVJquB
root image 
   
http://imgur.com/59UMCLB

 i'm using sentora on ubuntu server with 2tb storage and 16gb ram, i allocated root storage for about 90gb. now when i check the root storage use it shows 95%full, when i check the files from ftp there is only few mb of files there. 
what is the problem how can i free up the root space. 
thank you

[Me.B]

depend on your VPS image seem the partitions here are wrong.

[TGates]

Also you may want to delete/clean out your log files to make more space. (/var/logs/, /var/sentora/logs/)