How to check Sharepoint storage usage for the site in Sharepoint Central Administration.
- Find out Sharepoint domain name - in subscription CCP go to 'Sharepoint' tab and note the domain name.
- Go to Top > Service Director > Shared Hosting Manager > Websites, enter domain name and check on which host it is located.
- Login to the host found in step 2.
- Enter Sharepoint Central Administration with credentials used in step 3.
- Go to 'Site Collection Quotas and Locks', search needed site in 'Site Collection' drop down menu, select the site and check quota information.