If you close an operating system session where a database server is running, or if you use an operating system command to stop the database server, the server shuts down, but not cleanly. The next time the database loads, recovery is required, and happens automatically.

For more information about recovery, see Backup and data recovery.

It is better to stop the database server explicitly before closing the operating system session.

Examples of commands that do not stop a server cleanly include:

• Stopping the process in the Windows Task Manager
• Using a Unix slay or kill command