日志组建议每个线程在3组以上。为保障redo日志文件的安全,如果规划了多个ASM磁盘组,可将每组redo日志设置两个成员并分布到不同的ASM磁盘组上。日志大小和组数依据高峰期不出现redo切换等待为基准。
1.检查当前 redo logfile 配置 (RAC01)
sqlplus / as sysdba
SQL >
set linesize 200
col member for a60
select * from v$log;
select * from v$logfile;
2.添加日志组 (RAC01)
SQL >
ALTER DATABASE ADD LOGFILE THREAD 1 GROUP 11 '+DATA' SIZE 1G;
ALTER DATABASE ADD LOGFILE THREAD 2 GROUP 12 '+DATA' SIZE 1G;
ALTER DATABASE ADD LOGFILE THREAD 3 GROUP 13 '+DATA' SIZE 1G;
ALTER DATABASE ADD LOGFILE THREAD 4 GROUP 14 '+DATA' SIZE 1G;
3.切换日志(RAC01/RAC02)
注:切换日志,使新建日志组11/12/13/14的状态 STATUS 是 CURRENT。
SQL >
ALTER SYSTEM SWITCH LOGFILE;
ALTER SYSTEM SWITCH LOGFILE;
ALTER SYSTEM SWITCH LOGFILE;
ALTER SYSTEM SWITCH LOGFILE;
ALTER SYSTEM CHECKPOINT;
SELECT * FROM V$LOG;
4.删除日志组 1/2/3/4(RAC01)
注:日志组 STATUS 是 INACTIVE 时删除。
SQL >
ALTER DATABASE DROP LOGFILE GROUP 1;
ALTER DATABASE DROP LOGFILE GROUP 2;
ALTER DATABASE DROP LOGFILE GROUP 3;
ALTER DATABASE DROP LOGFILE GROUP 4;
SELECT * FROM V$LOG;