Oracle : Ошибка ORA-01530

"a database already mounted by the instance"
*Cause: During ALTER DATABASE MOUNT, an attempt is being made to mount
a database on an instance in which a database is or has previously
been mounted.
*Action: If you wish to mount the database, shutdown the instance
and then startup the instance and retry the operation.

Попробовать перевести

Поискать эту ошибку на форуме