************************************************************************ ****原文： blog.csdn.net/clark_xu 徐长亮的专栏 ************************************************************************ rac需要至少需要四个日志组，分配到每个线程上各
************************************************************************ ****原文： blog.csdn.net/clark_xu 徐长亮的专栏 ************************************************************************rac需要至少需要四个日志组，分配到每个线程上各两组，两个线程的日志组不共享。
一、查看各个节点的线程分配：
节点一
SQL> show parameters thread
NAME TYPE VALUE
----------------------------------------------- ------------------------------
parallel_threads_per_cpu integer 2
thread integer 1
节点 2
SQL> show parameters thread
NAME TYPE VALUE
----------------------------------------------- ------------------------------
parallel_threads_per_cpu integer 2
thread integer 2
二、查看默认组对应的线程
SQL> select group#,thread#,members from v$log;
GROUP# THREAD# MEMBERS
---------- ---------- ----------
1 1 2
2 1 2
3 2 2
4 2 2
三、常见的日志组规划：每个线程6组，每个组的两个成员放在不同的位置
redo 日志组 线程 成员 位置 大小 Group 1 thread 1 member 1 +DGDATA 1GB member 2 +DGFRA 1GB Group 2 thread 1 member 1 +DGDATA 1GB member 2 +DGFRA 1GB Group 3 thread 2 member 1 +DGDATA 1GB member 2 +DGFRA 1GB Group 4 thread 2 member 1 +DGDATA 1GB member 2 +DGFRA 1GB Group 5 thread 1 member 1 +DGDATA 1GB member 2 +DGFRA 1GB Group 6 thread 1 member 1 +DGDATA 1GB member 2 +DGFRA 1GB Group 7 thread 1 member 1 +DGDATA 1GB member 2 +DGFRA 1GB Group 8 thread 1 member 1 +DGDATA 1GB member 2 +DGFRA 1GB Group 9 thread 2 member 1 +DGDATA 1GB member 2 +DGFRA 1GB Group 10 thread 2 member 1 +DGDATA 1GB member 2 +DGFRA 1GB Group 11 thread 2 member 1 +DGDATA 1GB member 2 +DGFRA 1GB Group 12 thread 2 member 1 +DGDATA 1GB member 2 +DGFRA 1GB
四、添加日志组
SQL> ALTER DATABASE ADD LOGFILE THREAD 1GROUP 5 ('+DGDATA','+DGFRA') SIZE 1024M;
Database altered.
SQL> ALTER DATABASE ADD LOGFILE THREAD 1GROUP 6 ('+DGDATA','+DGFRA') SIZE 1024M;
Database altered.
SQL> ALTER DATABASE ADD LOGFILE THREAD 1GROUP 7 ('+DGDATA','+DGFRA') SIZE 1024M;
Database altered.
SQL> ALTER DATABASE ADD LOGFILE THREAD 1GROUP 8 ('+DGDATA','+DGFRA') SIZE 1024M;
Database altered.
SQL> ALTER DATABASE ADD LOGFILE THREAD 2GROUP 9 ('+DGDATA','+DGFRA') SIZE 1024M;
Database altered.
SQL> ALTER DATABASE ADD LOGFILE THREAD 2GROUP 10 ('+DGDATA','+DGFRA') SIZE 1024M;
Database altered.
SQL> ALTER DATABASE ADD LOGFILE THREAD 2GROUP 11 ('+DGDATA','+DGFRA') SIZE 1024M;
Database altered.
SQL> ALTER DATABASE ADD LOGFILE THREAD 2GROUP 12 ('+DGDATA','+DGFRA') SIZE 1024M;
Database altered.
五、修改当前日志组，为了能删除默认的四个日志组
SQL> alter system switch logfile;
System altered.
SQL> alter system switch logfile;
System altered.
SQL> alter system switch logfile;
System altered.
SQL> alter system switch logfile;
Systemaltered.
SQL> alter system checkpoint;
System altered.
六、删除和新建日志组
SQL> alter database drop logfile group1;
Database altered.
SQL> alter database drop logfile group 3;
Database altered.
SQL> alter database drop logfile group 2;
Database altered.
SQL> alter database drop logfile group 4;
Database altered.
七、添加日志组
SQL> ALTER DATABASE ADD LOGFILE THREAD 1GROUP 1 ('+DGDATA','+DGFRA') SIZE 1024M;
Database altered.
SQL> ALTER DATABASE ADD LOGFILE THREAD 1GROUP 2 ('+DGDATA','+DGFRA') SIZE 1024M;
Database altered.
SQL> ALTER DATABASE ADD LOGFILE THREAD 2GROUP 3 ('+DGDATA','+DGFRA') SIZE 1024M;
Database altered.
SQL> ALTER DATABASE ADD LOGFILE THREAD 2GROUP 4 ('+DGDATA','+DGFRA') SIZE 1024M;
Database altered.
八、查看，确认
SQL> select group#,thread#,members fromv$log;
GROUP# THREAD# MEMBERS
---------- ---------- ----------
1 1 2
2 1 2
3 2 2
4 2 2
5 1 2
6 1 2
7 1 2
8 1 2
9 2 2
10 2 2
11 2 2
GROUP# THREAD# MEMBERS
---------- ---------- ----------
12 2 2
12 rows selected
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