resize redo log files

Now i am going to describe how i have done this. The procedure was learned from a release note of metalink .



1. First see the size of the current logs:

SQL> connect / as sysdba

SQL> select group#, bytes, status from v$log;
GROUP# BYTES STATUS
---------- ---------- ----------------
1 52428800 INACTIVE
2 52428800 CURRENT
3 52428800 INACTIVE

Logs are 50MB from above which is default in oracle 10g, let's size them to 100MB.


2. Retrieve all the log member names for the groups:

SQL> select group#, member from v$logfile;

GROUP# MEMBER
--------------- ----------------------------------------
1 /usr/oracle/dbs/log1PROD.dbf
2 /usr/oracle/dbs/log2PROD.dbf
3 /usr/oracle/dbs/log3PROD.dbf


3. Now drop the log group 1 and recreate it with increased size

SQL> alter database drop logfile group 1;

SQL> alter database add logfile group 1
'/usr/oracle/dbs/log1PROD.dbf' size 100M reuse;

4. Check the size of the current logs:

SQL> connect / as sysdba

SQL> select group#, bytes, status from v$log;
GROUP# BYTES STATUS
---------- ---------- ----------------
1 10485760 UNUSED
2 52428800 CURRENT
3 52428800 INACTIVE
5. Do the same for log group 3

SQL> alter database drop logfile group 3;

SQL> alter database add logfile group 3
'/usr/oracle/dbs/log3PROD.dbf' size 100M reuse;


SQL> select group#, bytes, status from v$log;
GROUP# BYTES STATUS
---------- ---------- ----------------
1 10485760 UNUSED
2 52428800 CURRENT
3 10485760 INACTIVE
6. Now we go for group 2 but it is now used by oracle, so first switch the log

SQL> alter system switch logfile;

SQL> select group#, bytes, status from v$log;
GROUP# BYTES STATUS
---------- ---------- ----------------
1 10485760 UNUSED
2 52428800 INACTIVE
3 10485760 CURRENT
SQL> alter database drop logfile group 2;


SQL> alter database add logfile group 2
'/usr/oracle/dbs/log2PROD.dbf' size 100M reuse;

7. Check the size of the current logs:

SQL> connect / as sysdba

SQL> select group#, bytes, status from v$log;
GROUP# BYTES STATUS
---------- ---------- ----------------
1 10485760 UNUSED
2 10485760 UNUSED
3 10485760 CURRENT

** some times you may find that a log group status is ACTIVE, in that case you should
make a database checkpoint like this

SQL> ALTER SYSTEM CHECKPOINT;

** FOR safety reason please take full backup