Step 1 :- Check your online redo log file group and members
sql> select a.group#, a.member, b.bytes
2 FROM v$logfile a, v$log b WHERE a.group# = b.group#;
group# member bytes
1 D:\oracle\product\10.2.0\oradata\orcl\redo01.log 52428800
2 D:\oracle\product\10.2.0\oradata\orcl\redo02.log 52428800
3 D:\oracle\product\10.2.0\oradata\orcl\redo03.log 52428800
Step 2:
Forcing a log switch logfile
step 3:
sql> select group#, status from v$log;
group# status
1 inactive
2 current
3 inactive
sql> alter system switch logfile;
sql> alter system switch logfile;
sql> select group#, status from v$log;
group# status
1 active
2 active
3 current
Now we try to drop the group 1, we can face errors
SQL> ALTER DATABASE DROP LOGFILE GROUP 1;
ALTER DATABASE DROP LOGFILE GROUP 1
*
ERROR at line 1:
ORA-01624: log 1 needed for crash recovery of instance ORA920 (thread 1)
ORA-00312: online log 1 thread 1: ‘file_name’
sql>alter system checkpoint global;
system altered.
sql> alter database drop logfile group 1;
Database altered.
Step 4: Recreate the redolog file
SQL> alter database add logfile group 1 (‘D:\oracle\product\10.2.0\oradata\orcl\redo01.log’) size 100m reuse;
Database altered.
sql> select group#, status from v$log;
group# status
1 unused
2 in active
3 current
V$LOG
UNUSED
– Online redo log has never been written to. This is the state of a redo log that was just added, or just after a RESETLOGS
, when it is not the current redo log.
CURRENT
– Current redo log. This implies that the redo log is active. The redo log could be open or closed.
ACTIVE
– Log is active but is not the current log. It is needed for crash recovery. It may be in use for block recovery. It may or may not be archived.
CLEARING
– Log is being re-created as an empty log after an ALTER DATABASE CLEAR LOGFILE
statement. After the log is cleared, the status changes to UNUSED
.
CLEARING_CURRENT
– Current log is being cleared of a closed thread. The log can stay in this status if there is some failure in the switch such as an I/O error writing the new log header.
INACTIVE
– Log is no longer needed for instance recovery. It may be in use for media recovery. It might or might not be archived.
INVALIDATED
– Archived the current redo log without a log switch.
Why we are not altering Resize logfile
Refer :
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:55812348055