restore redo log file

Restore the missing redo log file by dropping the lost redo log member and add a new member.

If the group with the missing logfile has been archived, clear the log group and re-create the missing member.

The steps for this operation are as follows:

SQL> conn sys/orcl@to_primary as sysdba;
Connected to an idle instance.
SQL> startup mount;
ORACLE instance started.
 Total System Global Area 2499805184 bytes
Fixed Size                  8749920 bytes
Variable Size             687869088 bytes
Database Buffers         1795162112 bytes
Redo Buffers                8024064 bytes
Database mounted.
 ---- Check which log groups has been archived
SQL> select group#,status,archived from v$log;
     GROUP# STATUS           ARC
---------- ---------------- ---
         1 INACTIVE         YES
         3 INACTIVE         YES
         2 CURRENT          NO
 SQL> alter database clear unarchived logfile group 2;
 Database altered.
 SQL> alter database open;
 Database altered.
 SQL>