【ORACLE RAC】日志组管理

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****原文：blog.csdn.net/clark_xu  徐长亮的专栏

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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