整理一份DG环境下增删主备库REDO的最佳实践步骤
1. 主库,备库都增加redo步骤说明:
主库可正常添加 ORLS（REDO LOG)或SRLS（STANDBY REDO LOG）
主库的STANDBY_FILE_MANAGEMENT无论是否auto 或Manuals都不会传播到备库, 但是为了避免主备切换后，欧博redo不足问题，所以建议备库也相应的添加redo .
FOR ADG:
RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE DISCONNECT FROM SESSION;FOR DG:
RECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION; 2. 只是备库添加REDO步骤(主库不添加) 2.1. 备库停复制: RECOVER MANAGED STANDBY DATABASE CANCEL; 2.2. 备库改手动 ALTER SYSTEM SET STANDBY_FILE_MANAGEMENT='MANUAL'; 2.3. 备库填加redo ALTER DATABASE ADD LOGFILE GROUP ... 2.4. 备库填加standby redo ALTER DATABASE ADD STANDBY LOGFILE GROUP ...RAC环境示例:
ALTER DATABASE ADD LOGFILE THREAD 1 GROUP 27 '+DG_DATA' SIZE 1024M, GROUP 28 '+DG_DATA' SIZE 1024M, GROUP 29 '+DG_DATA' SIZE 1024M; ALTER DATABASE ADD LOGFILE THREAD 2 GROUP 33 '+DG_DATA' SIZE 1024M, GROUP 34 '+DG_DATA' SIZE 1024M, GROUP 35 '+DG_DATA' SIZE 1024M, GROUP 36 '+DG_DATA' SIZE 1024M; 2.5. 备库改自动 ALTER SYSTEM SET STANDBY_FILE_MANAGEMENT='AUTO'; 2.6. 恢复复制FOR ADG:
RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE DISCONNECT FROM SESSION;FOR DG:
RECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION; 3. 删除redo(视需要)注：
无论主备，欧博娱乐current ,CLEARING_CURRENT不能删
备库要cancel 后才能删；
删除REDO和STANDBY_FILE_MANAGEMENT参数无关;
3.1. 备库停复制
RECOVER MANAGED STANDBY DATABASE CANCEL;3.2. 主库删除redo
alter system switch logfile; selecct * from v$Log; alter database clear logfile group 1; alter database drop logfile group 1;3.3. 主库删除stadnby redo
selecct * from v$Log; alter database clear logfile group 21; alter database drop standby logfile group 21;3.3. 备库删除redo
select * from v$Log; --注: 只有为CLEARING, UNUSED, INACTIVE 的才可继续执行如下删除. 如果是其他状态如current 状态，可在主库先进行switch logfile操作,再查看状态 是否改变; alter database clear logfile group 1; alter database drop logfile group 1;3.4. 备库删除stanby redo
alter database clear logfile group 21; alter database drop standby logfile group 21;3.5. 备库恢复复制
....
FYI:
MOS Note 740675.1 provides information on how to add ORLs.
