DG物理standby，failover步驟

DG物理standby，failover步驟

       環境為11gR2，oracle linux 6.4；物理standby，單例項；假設primary（db20）異常關閉資料庫，需要切換物理standby（db66）為新primary 資料庫；

步驟1：檢查歸檔日誌是否缺失

       如果異常的primary資料庫還能夠mount上，則啟動到mount狀態，然後執行SQL,補發日誌；

       SQL> ALTER SYSTEM FLUSH REDO TO target_db_name;

target_db_name 為db_unique_name，log_archive_dest_n中指定的；如果執行成功，則可以保證資料無丟失；

       如果異常主庫不能mount，則需要複製備庫缺失的歸檔日誌到備庫，然後註冊；

               SQL> ALTER DATABASE REGISTER PHYSICAL LOGFILE 'filespec1';

 

步驟2：備庫停止redo應用

       db66：

       SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;

 

步驟3：手動完成所有redo應用

       SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE FINISH;

如果執行沒有報任何錯誤，則執行步驟4；如果報錯並不能夠解決，則執行activate，    SQL> ALTER DATABASE ACTIVATE PHYSICAL STANDBY DATABASE;

然後執行步驟6；

 

步驟4：查詢備庫狀態

       SQL> SELECT SWITCHOVER_STATUS FROM V$DATABASE;

SWITCHOVER_STATUS

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

TO PRIMARY

1 row selected

如果SWITCHOVER_STATUS 為TO PRIMARY 或 SESSIONS ACTIVE值，為正常狀態，可以switchover為primary；

 

步驟5：切換到主庫

       SQL> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY WITH SESSION SHUTDOWN;

 

步驟6：開啟新主庫到open

       SQL> ALTER DATABASE OPEN;

       開啟新主庫；備份新主庫，然後啟動其他物理備庫已經停止的日誌應用；

 

開啟新主庫是報錯：

SQL> startup open

ORACLE instance started.

 

Total System Global Area  839282688 bytes

Fixed Size                  2233000 bytes

Variable Size             637537624 bytes

Database Buffers          192937984 bytes

Redo Buffers                6574080 bytes

Database mounted.

ORA-03113: end-of-file on communication channel

Process ID: 12427

Session ID: 191 Serial number: 3

 

檢視alert日誌檔案，如下：

Error 12514 received logging on to the standby

LGWR: Error 12514 verifying archivelog destination LOG_ARCHIVE_DEST_2

Destination LOG_ARCHIVE_DEST_2 is UNSYNCHRONIZED

LGWR: Continuing...

LGWR: Minimum of 1 applicable standby database required

Errors in file /u01/app/oracle/diag/rdbms/db66/oradb/trace/oradb_lgwr_12367.trc:

ORA-16072: a minimum of one standby database destination is required

LGWR (ospid: 12367): terminating the instance due to error 16072

System state dump requested by (instance=1, osid=12367 (LGWR)), summary=[abnormal instance termination].

System State dumped to trace file /u01/app/oracle/diag/rdbms/db66/oradb/trace/oradb_diag_12357.trc

Dumping diagnostic data in directory=[cdmp_20140228172732], requested by (instance=1, osid=12367 (LGWR)), summary=[abnormal instance termination].

Instance terminated by LGWR, pid = 12367

       透過上面的內容，發現報錯在歸檔日誌位置LOG_ARCHIVE_DEST_2，這個引數設定DG下primary資料庫的日誌傳送；由於原來的DG是maximize protect模式，而在failover後，原primary無法達到，則報錯；修改DG的保護模式為maximize availability即可

SQL> alter database set standby database to maximize availability;

 

Database altered.

SQL> select protection_mode,protection_level from v$database;

 

PROTECTION_MODE      PROTECTION_LEVEL

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

MAXIMUM AVAILABILITY RESYNCHRONIZATION