11g Dataguard维护手册



1.启动备库至standby状态

Sqlplus /as sysdba

Startupmount

Alter database recover managed standby database disconnect fromsession;      启动redo apply通过archivelog文件

Alter database recover managed standby database cancel;   停止redo apply

 

Alter database recover managed standby database using currentlogfile disconnect from session;  启动redo apply以real-time apply方式

Alter database recover managed standby database cancel;   停止apply

 

2.查询状态

SELECT SEQUENCE#,FIRST_TIME, NEXT_TIME FROM V$ARCHIVED_LOG ORDER BY SEQUENCE#;

SELECTSEQUENCE#,APPLIED FROM V$ARCHIVED_LOG ORDER BY SEQUENCE#;

selectdatabase_role,protection_mode,protection_level from v$database;

SELECTSWITCHOVER_STATUS FROM V$DATABASE;

 

3.switchover切换角色

主库上执行：

CONNECT / AS SYSDBA

ALTER DATABASECOMMIT TO SWITCHOVER TO STANDBY;

SHUTDOWN IMMEDIATE;

 

-- Mount old primarydatabase as standby database

STARTUP NOMOUNT;

ALTER DATABASE MOUNTSTANDBY DATABASE;

ALTER DATABASERECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION;

 

备库上执行：

CONNECT / AS SYSDBA

ALTER DATABASECOMMIT TO SWITCHOVER TO PRIMARY;

SHUTDOWN IMMEDIATE;

-- Open old standbydatabase as primary

STARTUP;

 

4.Failover

如果主库down掉了不能用了,则可以通过failover将备库启动为主库来使用，但是这样会破坏DG环境,如果原来的主库又恢复正常了,则只能从新配DG,或者

通过flashback来操作。前提是备库之前是开了flashback功能的。

failover的具体操作命令:注意是在备库上

Alterdatabase recover managed standby database finish;

Alterdatabase active standby database;

Alterdatabase open;

 

5 .Activedata guard

在11g之前standby库以read only 模式打开只能查询,不能redo apply

SHUTDOWN IMMEDIATE;

STARTUP MOUNT;

ALTER DATABASE OPENREAD ONLY;

 

如果启用redo apply,就不能查询数据

SHUTDOWN IMMEDIATE;

STARTUP MOUNT;

ALTER DATABASERECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION;

 

在11g里使用了active data gaurd特性就可以以read only模式打开,并且启用redao apply

SHUTDOWN IMMEDIATE;

STARTUP MOUNT;

ALTER DATABASE OPENREAD ONLY;

ALTER DATABASERECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE DISCONNECT FROM SESSION;

 

6.ProtectionMode

 Maximum Availability:Transactions on the primary do not commit until redo information has beenwritten to the online redo log and the standby redo logs of at least onestandby location. If no standby location is available, it acts in the samemanner as maximum performance mode until a standby becomes available again.

 

Maximum Performance:Transactions on the primary commit as soon as redo information has been writtento the online redo log. Transfer of redo information to the standby server isasynchronous, so it does not impact on performance of the primary.

 

Maximum Protection:Transactions on the primary do not commit until redo information has beenwritten to the online redo log and the standby redo logs of at least onestandby location. If not suitable standby location is available, the primarydatabase shuts down.

 

Bydefault, for a newly created standby database, the primary database is inmaximum performance mode.

 

SELECTprotection_mode FROM v$database;

 

PROTECTION_MODE

--------------------

MAXIMUM PERFORMANCE

 

The modecan be switched using the following commands. Note the alterations in the redotransport attributes.

-- MaximumAvailability.

ALTERSYSTEM SET LOG_ARCHIVE_DEST_2='SERVICE=standbyAFFIRM SYNC VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=standby';

ALTER DATABASE SETSTANDBY DATABASE TO MAXIMIZE AVAILABILITY;

 

-- MaximumPerformance.

ALTERSYSTEM SET LOG_ARCHIVE_DEST_2='SERVICE=standby NOAFFIRM ASYNC VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE)DB_UNIQUE_NAME=standby';

ALTER DATABASE SETSTANDBY DATABASE TO MAXIMIZE PERFORMANCE;

 

-- MaximumProtection.

ALTERSYSTEM SET LOG_ARCHIVE_DEST_2='SERVICE=standby AFFIRM SYNC VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE)DB_UNIQUE_NAME=standby';

SHUTDOWN IMMEDIATE;

STARTUP MOUNT;

ALTER DATABASE SETSTANDBY DATABASE TO MAXIMIZE PROTECTION;

ALTER DATABASE OPEN;