在生产环境中，高性能服务器的RAC将默认日志50M扩大，有助于性能提升

1.查看当前默认日志组

SQL> select GROUP#,THREAD#,SEQUENCE#,BYTES,MEMBERS,ARCHIVED,STATUS from v$log;

GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS
---------- ---------- ---------- ---------- ---------- --- ----------------
1 1 821 52428800 1 YES INACTIVE
2 1 822 52428800 1 NO CURRENT
3 2 241 52428800 1 YES INACTIVE
4 2 242 52428800 1 NO CURRENT

2.添加日志组和成员

节点1
alter database add logfile thread 1 group 11 ('+DATA/funddb/onlinelog/redo11a.log','+DATA/funddb/onlinelog/redo11b.log') size 500M;
alter database add logfile thread 1 group 12 ('+DATA/funddb/onlinelog/redo12a.log','+DATA/funddb/onlinelog/redo12b.log') size 500M;
alter database add logfile thread 1 group 13 ('+DATA/funddb/onlinelog/redo13a.log','+DATA/funddb/onlinelog/redo13b.log') size 500M;

节点2
alter database add logfile thread 2 group 14 ('+DATA/funddb/onlinelog/redo14a.log','+DATA/funddb/onlinelog/redo14b.log') size 500M;
alter database add logfile thread 2 group 15 ('+DATA/funddb/onlinelog/redo15a.log','+DATA/funddb/onlinelog/redo15b.log') size 500M;
alter database add logfile thread 2 group 16 ('+DATA/funddb/onlinelog/redo16a.log','+DATA/funddb/onlinelog/redo16b.log') size 500M;

3.切换日志

节点1
SQL> alter system switch logfile;

System altered.

节点2
SQL> alter system switch logfile;

System altered.

4.查询并等待

SQL> select GROUP#,THREAD#,SEQUENCE#,BYTES,MEMBERS,ARCHIVED,STATUS from v$log;

GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS
---------- ---------- ---------- ---------- ---------- --- ----------------
1 1 821 52428800 1 YES INACTIVE
2 1 822 52428800 1 YES ACTIVE
3 2 241 52428800 1 YES INACTIVE
4 2 242 52428800 1 YES ACTIVE
11 1 823 524288000 2 NO CURRENT
12 1 0 524288000 2 YES UNUSED
13 1 0 524288000 2 YES UNUSED
14 2 243 524288000 2 NO CURRENT
15 2 0 524288000 2 YES UNUSED
16 2 0 524288000 2 YES UNUSED

10 rows selected.

等待......

SQL> select GROUP#,THREAD#,SEQUENCE#,BYTES,MEMBERS,ARCHIVED,STATUS from v$log;

GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS
---------- ---------- ---------- ---------- ---------- --- ----------------
1 1 821 52428800 1 YES INACTIVE
2 1 822 52428800 1 YES INACTIVE
3 2 241 52428800 1 YES INACTIVE
4 2 242 52428800 1 YES INACTIVE
11 1 823 524288000 2 NO CURRENT
12 1 0 524288000 2 YES UNUSED
13 1 0 524288000 2 YES UNUSED
14 2 243 524288000 2 NO CURRENT
15 2 0 524288000 2 YES UNUSED
16 2 0 524288000 2 YES UNUSED

10 rows selected.

5.删除旧日志组

SQL> alter database drop logfile group 1;

Database altered.

SQL> alter database drop logfile group 2;

Database altered.

SQL> alter database drop logfile group 3;

Database altered.

SQL> alter database drop logfile group 4;

Database altered.

6.确认完成日志组的扩大

SQL> select GROUP#,THREAD#,SEQUENCE#,BYTES,MEMBERS,ARCHIVED,STATUS from v$log;

GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS
---------- ---------- ---------- ---------- ---------- --- ----------------
11 1 823 524288000 2 NO CURRENT
12 1 0 524288000 2 YES UNUSED
13 1 0 524288000 2 YES UNUSED
14 2 243 524288000 2 NO CURRENT
15 2 0 524288000 2 YES UNUSED
16 2 0 524288000 2 YES UNUSED

本文创建时间为2016年8月3日 15:25:00
作者：洪卓辉 kingsql
Oracle DBA，资深培训师
hongzhuohui@kingsql.com
转载请注明出处

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