To enable quota support in Cpanel on Redhat, you first must make
sure that /etc/fstab contains the usrquota directive. If it does not,
you can edit that file so that the entry for the partion you wish to
enable quotas on looks like this:



/dev/hda3              
/                      
ext3   
defaults,usrquota        1 1



After that, you reboot, you can log into WHM and click on “Initial Quota Setup”. This will enable quota support for your users.