As the VSS administrator, it is your job to manage the database. This includes analyzing the data folder to look for signs of database corruption, archiving the database when it becomes too large, and cleaning the Temp folder.
You may need to lock the database before you can perform some of these actions, in order to keep user actions from interfering.
Sometimes a user inadvertently leaves a file checked out. If the user cannot be located, the VSS administrator can undo the user's checkout.
For information on how to manage the database, refer to: