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How to retrieve lost control file ORA-00210: cannot open the specified control file To simulate the situation of a lost control file or disk failure, I deleted a control file while the Oracle Database was running. SQL> alter database datafile '/u02/app/oracle/oradata/mynewdb/users01.dbf' resize 512M; Database altered.  SQL> ! rm -f /u02/app/oracle/oradata/mynewdb/control01.ctl Then I shutdown the database. SQL> shutdown immediate; Database closed. ORA-00210: cannot open the specified control file ORA-00202: control file: '/u02/app/oracle/oradata/mynewdb/control01.ctl' ORA-27041: unable to open file Linux Error: 2: No such file or directory Additional information: 3 Then I start the database up. SQL> startup ORA-01081: cannot start already-running ORACLE - shut it down first SQL> select open_mode from v$database; select open_mode from v$database           ...

ora-16196 database has been previously opened and closed There are two terms that, when used in an Oracle context, seem to cause a great deal of confusion: ‘Instance’ and ‘Database’. In Oracle terminology, the definitions of these terms is as follows: Database : A collection of physical operating system files or disk. When using Oracle 10g or above, Automatic Storage Management (ASM) or RAW partitions, the database may not appear as individual separate files in the operating system, but the definition remains the same. Instance : A set of Oracle background processes/threads and a shared memory area, which is the memory that is shared across those threads/processes running on a single computer.   This is the place to maintain volatile, non persistent stuff (some of which gets flushed to disk). A database instance can exist without any disk storage whatsoever. It might not be the most useful thing in the world, but thinking about it that way will definitely help draw ...

ORA-30036: unable to extend segment in tablespace Error: unable to extend segment by %s in undo tablespace %s Note: This is a general discussion which can be applied to any tablespace having this problem. The tablespace mentioned in the error is unable to extend. Reason for the Error: ~~~~~~~~~~~~~~~~~~~~~~~~~~~ There is not enough space left either due to the datafiles belonging to the tablespace are   being full,   autoextend which is not set at datafile level due to which they cannot increase in size whenever required or due to a disk which is full. You will have to check the size of the datafiles attached to the tablespace and check whether they can autoextend or not. Resolution for the Error: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Check if your disk or mount point containing database files (belonging to the respective tablespace) is not full. If it is full then provide your database with new disk(s) having enough free space on them. The...