Closes an open database.

    You should always specify the Wait qualifier, unless you are
    attempting to recover from some failure. When you specify the
    Wait qualifier, Oracle RMU performs all the auxiliary actions
    required to close and recover the database clusterwide, and it
    does not return the system prompt until those actions have been
    completed.

    If you use the RMU Close command with the Nowait qualifier, the
    database must be open on the node where you issue the command.
    Otherwise, you will receive an error message stating that the
    database is not known. The system prompt is returned immediately,
    but it is only an indication that the database will be closed
    as soon as all other users have finished accessing the database.
    Therefore, the Wait qualifier is used almost exclusively.