ORA - 00313, ORA -00312

ORA -00313 : open failed for members of log group string of thread string

Cause: The online log cannot be opened. May not be able to find file.

Action: See accompanying errors and make log available.

ORA - 00312
ORA-00312: online log 1 thread 1: '/u01/TESTDB3/oraredo/redo1a.log'
ORA-00312: online log 1 thread 1: '/u01/TESTDB3/oraredo/redo1b.log'

The above errors pop whenever you try to start the database.

Cause: Either the log file has been removed or the log file has been corrupted.

Action: Follow the steps below -

SQL> starup mount;
SQL> select status from v$log where group#=1;
If the status is not current them simply drop the log file as below:
SQL>alter database drop logfile group 1;
If required create another logfile group.
SQL>alter database add logfile group 3 '/u01/TESTDB3/oraredo/redo3a.log' size 10M;
SQL> recover database until cancel;
SQLalter database open resetlogs;