Online
    Noonline

    Specifying the Online qualifier permits users running active
    transactions at the time the command is entered to continue
    without interruption (unless the Noquiet_Point qualifier is also
    specified).

    Any subsequent transactions that start during the online backup
    operation are permitted as long as the transactions do not
    require exclusive access to the database, a table, or any index
    structure currently being backed up.

    To perform an online database backup operation, snapshots (either
    immediate or deferred) must be enabled. You can use the Online
    qualifier with the Incremental or Noincremental qualifiers.

    If you use the default, the Noonline qualifier, users cannot be
    attached to the database. If a user has invoked the database and
    the RMU Backup command is entered with the Noonline qualifier (or
    without the Online qualifier), an Oracle RMU error results. For
    example:

    %RMU-I-FILACCERR, error opening database root file DB_DISK:MF_PERSONNEL.RDB;1
    -SYSTEM-W-ACCONFLICT, file access conflict

    The offline backup process (specified with the Noonline
    qualifier) has exclusive access to the database and does not
    require snapshot (.snp) files in order to work. The snapshot
    files can be disabled when the Noonline qualifier is used.

    Oracle Corporation recommends that you close the database (with
    the RMU Close command) when you perform the offline backup
    operation on a large database. If the database was opened with
    the SQL OPEN IS MANUAL statement, the RMU Backup command will
    fail unless the RMU Close command is used. If the database was
    opened with the SQL OPEN IS AUTOMATIC statement, the RMU Backup
    command might fail if the activity level is high (that is, users
    might access the database before the database is taken off line).
    Issuing the RMU Close command can force the users out of the
    database and give the RMU Backup command a chance to start;
    however, although recommended, issuing the RMU Close command
    is not required in this case.

    Synonymous with the Owner qualifier. See the description of the
    Owner qualifier.