There are some reasons for a file being created as
UNNAMED in the standby database, including insufficient disk space on the standby site, non-privileged directory structure on standby database, or improper parameter settings related to file management.
STANDBY_FILE_MANAGEMENT parameter enables or disables automatic standby file management in Data Guard. When automatic standby file management is enabled, file additions and deletions in the primary database are replicated to the standby database.
For example, we add a datafile in the primary database when the
STANDBY_FILE_MANAGEMENT parameter on the standby database is set to
MANUAL. Due to this parameter setting, it will create an
UNNAMED file under