Oracle ADG 切换场景及具体切换步骤
来自社区交流分享
■ 计划内切换
（1）检查主库
select switchover_status from v$database;
SWITCHOVER_STATUS
SESSIONS ACTIVE
if [ switchover_status = "SESSIONS ACTIVE" | switchover_status = "TO STANDBY" ];
then { go to next step }
else { cancel switchover and check database }
（2）主库切为备库
alter database commit to switchover to physical standby with session shutdown;
shutdown immediate;
startup mount;
（3）检查备库
select switchover_status from v$database;
SWITCHOVER_STATUS
TO PRIMARY
if [ switchover_status = "SESSIONS ACTIVE" | switchover_status = "TO PRIMARY" ];
then { go to next step }
else { cancel switchover and check database }
（4）备库切为主库
alter database commit to switchover to PRIMARY with session shutdown;
（5）原主库恢复日志应用
alter database recover managed standby database using current logfile disconnect from session;
■ 计划外切换
一、主备库日志没有缺口的场景
（1）备库检查日志缺口
select thread#,low_sequence#,high_sequence# from v$archive_gap;
未选定行
（2）备库停止日志接受并完成已收日志应用
alter database recover managed standby database cancel;
alter database recover managed standby database finish;
（3）检查备库状态
select switchover_status from v$database;
SWITCHOVER_STATUS
TO PRIMARY
if [ switchover_status = "SESSIONS ACTIVE" | switchover_status = "TO PRIMARY" ];
then { go to next step }
else { cancel switchover and check database }
（4）备库切为主库
alter database commit to switchover to PRIMARY with session shutdown;
alter database open;
二、主库可以打开到 mount 状态
（1）将主库日志刷到备库
alter system flush redo to target_db_name;
（2）备库停止日志接受并完成已收日志应用
alter database recover managed standby database cancel;
alter database recover managed standby database finish;
（3）检查备库状态
select switchover_status from v$database;
SWITCHOVER_STATUS
TO PRIMARY
if [ switchover_status = "SESSIONS ACTIVE" | switchover_status = "TO PRIMARY" ];
then { go to next step }
else { cancel switchover and check database }
（4）备库切为主库
alter database commit to switchover to PRIMARY with session shutdown;
alter database open;
三、主备库间日志缺口无法纠正
（1）强制激活备库
alter database activate physical standby database;
alter database open;
更多相关文章请点击阅读原文
长按二维码关注公众号