One of the very useful features of cPanel’s WebHost Manager (WHM) is the ability to control user quotas, the amount of disk space allotted to a given user account. Once an account reaches its disk quota, no more files can be added.
To modify an account’s quota, navigate WHM to Home >> Account Functions >> Quota Modification. There, you will find a list of the accounts.
Click on the account you wish to modify or search for it using “account search”
You can then either choose to modify a single quota or all of the users’ quotas
Enter the quota amount (in megabytes)
Account quotas are a good way to ensure that your customers do not abuse their accounts, even accidentally, by using more than their fair share of disk space. Even if you theoretically offer “unlimited” space, you might want to set a high maximum, since no server actually has unlimited disk space, even if you are continuously adding drives. If necessary, you can always go back and raise the quota for any or all users.