[Oracle DataBase Server 12.1 installation on Windows 2008 Server]: Redologs multiplexing


md e:\app\oracle\oradata\ora121\redo
md f:\app\oracle\oradata\ora121\redo



sqlplus / as sysdba

Command to present output result in convenient format

SQL> set linesize 250;
SQL> set pagesize 0;
SQL> col  GROUP# format 99;
SQL> col  MEMBER format a40;
SQL> col  STATUS format a10;
SQL> col  MB format 999;



SQL> select a.group#, member, a.status, bytes/1024/1024 as "MB"
from v$log a, v$logfile b
where a.group# = b.group#
order by 1;



1 E:\APP\ORACLE\ORADATA\ORA121\REDO01.LOG  INACTIVE     50
2 E:\APP\ORACLE\ORADATA\ORA121\REDO02.LOG  INACTIVE     50
3 E:\APP\ORACLE\ORADATA\ORA121\REDO03.LOG  CURRENT      50


You could remove only files in not active group. You could switch groups. We will show how to do it later.

Now we remove files from INACTIVE group



1) We should recreate group 1 and files from this group.

Remove files group 1

SQL> alter database drop logfile group 1;



SQL> quit



del E:\APP\ORACLE\ORADATA\ORA121\REDO01.LOG



$ sqlplus / as sysdba

To add new group with files:

SQL> alter database add logfile group 1 ('e:\app\oracle\oradata\ora121\redo\redo01.log', 'f:\app\oracle\oradata\ora121\redo\redo01.log') size 100M;



2) We should recreate group 2 and files from this group.

Remove files group 2

SQL> alter database drop logfile group 2;



SQL> quit



del E:\APP\ORACLE\ORADATA\ORA121\REDO02.LOG



$ sqlplus / as sysdba



SQL> alter database add logfile group 2 ('e:\app\oracle\oradata\ora121\redo\redo02.log', 'f:\app\oracle\oradata\ora121\redo\redo02.log') size 100M;


3) We should recreate group 3 and files from this group.

Because this group is active, we should to switch current group to next. Group 3 should be INACTIVE.

For switch execute next command:


SQL> alter system checkpoint;
SQL> alter system switch logfile;

Remove files group 3

SQL> alter database drop logfile group 3;



SQL> quit



del E:\APP\ORACLE\ORADATA\ORA121\REDO03.LOG



$ sqlplus / as sysdba



SQL> alter database add logfile group 3 ('e:\app\oracle\oradata\ora121\redo\redo03.log', 'f:\app\oracle\oradata\ora121\redo\redo03.log') size 100M;



SQL> set linesize 250;
SQL> set pagesize 0;
SQL> col  GROUP# format 99;
SQL> col  MEMBER format a40;
SQL> col  STATUS format a10;
SQL> col  MB format 999;



SQL> select a.group#, member, a.status, bytes/1024/1024 as "MB"
from v$log a, v$logfile b
where a.group# = b.group#
order by 1,2;



1 E:\APP\ORACLE\ORADATA\ORA121\REDO\REDO01.LOG CURRENT     100
1 F:\APP\ORACLE\ORADATA\ORA121\REDO\REDO01.LOG CURRENT     100
2 E:\APP\ORACLE\ORADATA\ORA121\REDO\REDO02.LOG UNUSED      100
2 F:\APP\ORACLE\ORADATA\ORA121\REDO\REDO02.LOG UNUSED      100
3 E:\APP\ORACLE\ORADATA\ORA121\REDO\REDO03.LOG UNUSED      100
3 F:\APP\ORACLE\ORADATA\ORA121\REDO\REDO03.LOG UNUSED      100



SQL> quit