Enable the Usage Summary page in SharePoint

The Usage Summary page is an administrative page that is useful for monitoring the size of the content database.  Normally,it is available from Site Settings on the parent site of a site collection.  However, if it does not show up, you probably need to enable usage logging by performing the following:

1. Central Admin
2. Operations
3. Under Logging and Reporting, click "Usage analysis processing"
4. Check "Enable logging" and "Enable usage analysis processing"
5. OK