Database server connection states
Users can only connect to database servers when the database servers are running. Database servers are configured to automatically start when the computer on which they are installed is started. To prevent users from connecting to the database server, you can stop or pause it.
Stopping or pausing the database server from within ArcGIS Desktop stops or pauses the SQL Server Express instance.
There are not many cases for which you will want to stop or pause a database server. You might stop a database server if an invalid connection persists to the database server, for instance, if a connecting application crashed but the connection remained.
Stopping the database server kills all current connections and prevents new connections from being made to it. If users are editing when you stop the database server, their changes could be lost or the data could become corrupted; therefore, be sure there are not any active, valid connections being made to the database server before you stop it.
Pausing the database server allows existing connections to remain, but prevents new connections from being made to the database server. You might pause a database server before performing administrative tasks such as a compress operation, a backup, or an upgrade. This prevents new connections from being made. Then, you can notify existing users to disconnect. When the users have done so, you can perform the administrative task.
When you are ready to allow users to connect to the database server again, you can start or resume it. You start a database server that was stopped; you resume a database server that was paused.