switchover to xxx 犯的低级错误

1.环境描述

ORACLE 12CR1

RHEL 7.0

2.操作过程

switchover to xxx 报错，过程如下：

<orcldg:orcldg:/home/oracle>$dgmgrl /
DGMGRL for Linux: Version 12.1.0.2.0 - 64bit Production

Copyright (c) 2000, 2013, Oracle. All rights reserved.

Welcome to DGMGRL, type "help" for information.
Connected as SYSDG.
DGMGRL> show configuration;

Configuration - dg_config

  Protection Mode: MaxAvailability
  Members:
  orcl   - Primary database
    orcldg - Physical standby database

Fast-Start Failover: DISABLED

Configuration Status:
SUCCESS   (status updated 14 seconds ago)

DGMGRL> validate database orcl;

  Database Role:    Primary database

  Ready for Switchover:  Yes

DGMGRL> validate database orcldg;

  Database Role:     Physical standby database
  Primary Database:  orcl

  Ready for Switchover:  Yes
  Ready for Failover:    Yes (Primary Running)

DGMGRL> switchover to orcldg;
Performing switchover NOW, please wait...
New primary database "orcldg" is opening...
Oracle Clusterware is restarting database "orcl" ...
ORA-01017: invalid username/password; logon denied

Warning: You are no longer connected to ORACLE.

        shut down instance "orcl" of database "orcl"
        start up instance "orcl" of database "orcl"

DGMGRL>
DGMGRL> connect sys/oracle@orcl
Connected as SYSDBA.
DGMGRL> switchover to orcldg;
Performing switchover NOW, please wait...
Error: ORA-16558: database specified for switchover is not a standby database

Failed.
Unable to switchover, primary database is still "orcldg"
DGMGRL> switchover to orcl;
Performing switchover NOW, please wait...
New primary database "orcl" is opening...
Oracle Clusterware is restarting database "orcldg" ...
Switchover succeeded, new primary is "orcl"
DGMGRL>