DG问题：ORA-16416: No viable Physical Standby switchover targets available

ORA-16416: No viable Physical Standby switchover targets availabl&ORA-16047&ORA-02097&ORA-16025& ORA-12154

1.报错信息：

ORA-16416: No viable Physical Standby switchover targets available
ORA-16047: DGID mismatch between destination setting
ORA-02097: parameter cannot be modified because specified value is invalid
ORA-16025: parameter LOG_ARCHIVE_DEST_2 contains repeated or conflicting attributes
ORA-12154: TNS:could not resolve the connect identifier specified

2.实际环境：

DG搭建完成，主备切换顺利，由备库切回主库出现问题，报错如上其他错误为后续处理产生。

SYS@stddb>alter database commit to switchover to physical standby;
alter database commit to switchover to physical standby
*
ERROR at line 1:
ORA-16416: No viable Physical Standby switchover targets available

3.解决：

排查过程：

1）查看是否存在GAP

SYS@stddb>select * from  V$ARCHIVE_GAP;

no rows selected

2) 查看归档进程状态

SYS@stddb>select process,status from v$managed_standby;

PROCESS   STATUS
--------- ------------
ARCH      CLOSING
ARCH      CLOSING
ARCH      CONNECTED
ARCH      CLOSING

3）查看此时备库的切换状态，为not allowed存在异常

SYS@stddb> select name,database_role,switchover_status from v$database;

NAME      DATABASE_ROLE    SWITCHOVER_STATUS
--------- ---------------- --------------------
PROE      PRIMARY          NOT ALLOWED

4）查看归档信息报错，确定报错原因。备库所指定的归档日志路径存在问题。

SYS@stddb>select status,error from v$archive_dest;

STATUS    ERROR
--------- -----------------------------------------------------------------
VALID     (null)
DISABLED  ORA-16047: DGID mismatch between destination setting and target
          database
ERROR at line 1:
ORA-02097: parameter cannot be modified because specified value is invalid
ORA-16025: parameter LOG_ARCHIVE_DEST_2 contains repeated or conflicting attributes
# 查看备库归档参数设置
SYS@stddb>show parameter log_archive_dest_2;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest_2                   string      service=stddb valid_for=(onlin
                                                 e_logfiles,primary_role) db_un
                                                 ique_name=pridb

5）这里参数的值存在问题，将stddb修改为了pridb（这里仍然不正确）。

SYS@stddb> alter system set log_archive_dest_2='service=proe valid_for=(online_logfiles,primary_role) db_unique_name=pridb' scope=both;

6）重新查看当前归档报错信，仍然不是有效的。

SYS@stddb>select status,error from v$archive_dest;

STATUS    ERROR
--------- -----------------------------------------------------------------
VALID     (null)
DEFERRED  (null)

7）手动启用备库切换后归档路径启用

SYS@stddb>alter system set log_archive_dest_state_2=enable;

System altered.
# 再次查看报错改变，为监听问题
SYS@stddb>select status,error from v$archive_dest;

STATUS    ERROR
--------- -----------------------------------------------------------------
VALID     (null)
ERROR     ORA-12154: TNS:could not resolve the connect identifier specified

#pridb为DG中的标识，数据库的服务名仍为proe。确定错误后进行相应修改
SYS@stddb>alter system set log_archive_dest_2='service=proe valid_for=(online_logfiles,primary_role) db_unique_name=pridb' scope=both;

System altered.

8）查看数据库角色以及切换状态已经恢复。

SYS@stddb>select name,database_role,switchover_status from v$database;

NAME      DATABASE_ROLE    SWITCHOVER_STATUS
--------- ---------------- --------------------
PROE      PRIMARY          TO STANDBY

问题解决，注意参数文件修改。

来自为知笔记(Wiz)