Oracle資料庫主備切換
阿新 • • 發佈：2018-12-07
主備庫切換原因：
1. switch：使用者主動切換；
2. failover：主庫出現故障，強行切換；
switch切換過程：先主庫再備庫
主庫
1. 檢視switchover_status：select database_role, switchover_status from v$database;
如果switchover_status為：to standby 則：
ALTER DATABASE COMMIT TO SWITCHOVER TO PHYSICAL STANDBY
否則用：ALTER DATABASE COMMIT TO SWITCHOVER TO PHYSICAL STANDBY WITH SESSION SHUTDOWN;
2. 重啟資料庫：
shutdown immediate;
startup nomount;
3. 以備庫mount
alter database mount standby database;
備庫
1. 應用redo：alter database recover managed standby database disconnect from session;
2. 檢視switchover_status：select database_role, switchover_status from v$database;
如果switchover_status為：to primary 則：ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY
否則用：ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY WITH SESSION SHUTDOWN;
3. 重啟資料庫
shutdown immediate;
startup;
failover 主備庫切換
1.. 停止日誌應用
alter database recover managed standby database cancel;
2. 關閉standby日誌傳輸
alter database recover managed standby database finish force; 3. 切換到primary
alter database commit to switchover to primary with session shutdown; 做這一步的時候，若存在gap，則會報ORA-16139:Switchover: Media recovery required - standby not in limbo 錯誤。 做測試的時候，若先起主庫再起備庫，且未等待備庫相關日誌傳輸完畢，就會出現這個問題。此時需要強制切換
alter database activate physical standby database; 4. 重啟資料庫到open狀態
alter database recover managed standby database cancel;
2. 關閉standby日誌傳輸
alter database recover managed standby database finish force; 3. 切換到primary
alter database commit to switchover to primary with session shutdown; 做這一步的時候，若存在gap，則會報ORA-16139:Switchover: Media recovery required - standby not in limbo 錯誤。 做測試的時候，若先起主庫再起備庫，且未等待備庫相關日誌傳輸完畢，就會出現這個問題。此時需要強制切換
alter database activate physical standby database; 4. 重啟資料庫到open狀態