DataGuard encountered problems such as ORA-01093 during Switchover Switching

1. The master database encountered a ORA-01093 error while converting the role of the physical master/Slave Database

SQL> select switchover_status from v $ database;
SWITCHOVER_STATUS
--------------------
Sessions active ---------- there is an ACTIVE session.
SQL> ALTER DATABASE COMMIT TO SWITCHOVER TO PHYSICAL STANDBY;
ALTER DATABASE COMMIT TO SWITCHOVER TO PHYSICAL STANDBY
*
ERROR at line 1:
ORA-01093: alter database close only permitted with no sessions connected

This error is caused by active sessions in the master database. The solution is as follows:
1. Kill the Active session and run the command again.
2. Add the with session shutdown command
Alter database commit to switchover to physical standby with session shutdown;

2. When the slave database is switched to the master database, the status is not allowed. You may need to recover or exit the recovery mode.

SQL> select switchover_status from v $ database;
SWITCHOVER_STATUS
--------------------
NOT ALLOWED
SQL> alter database commit to switchover to primary;
Alter database commit to switchover to primary
*
ERROR at line 1:
ORA-16139: media recovery required
Or: -- RECOVERY NEEDED
SQL> select switchover_status from v $ database;
SWITCHOVER_STATUS
--------------------
RECOVERY NEEDED
###############
SQL> alter database recover managed standby database disconnect from session;
Database altered.
SQL> select switchover_status from v $ database;
SWITCHOVER_STATUS
--------------------
TO PRIMARY
SQL> alter database commit to switchover to primary;
Database altered.

3. After the master database is switched to the slave database, the slave database does not: alter database recover managed standby database cancel; or yes, it is automatically disconnected. The log prompts:

Sun Apr 20 20:15:35 2014
Media Recovery Log/u01/app/Oracle/prod/arch/12762_844894247.dbf
Media Recovery Waiting for thread 1 sequence 63
Sun Apr 20 20:15:46 2014
Redo Shipping Client Connected as PUBLIC
-- Connected User is Valid
RFS [6]: Assigned to RFS process 19968
RFS [6]: Identified database type as 'physical standby'
RFS [6]: Archived Log: '/u01/app/oracle/prod/arch/201763_844894247.dbf'
Sun Apr 20 20:15:50 2014
Media Recovery Log/u01/app/oracle/prod/arch/10963_844894247.dbf
Identified End-Of-Redo for thread 1 sequence 63
Sun Apr 20 20:15:50 2014
Media Recovery End-Of-Redo indicator encountered
Sun Apr 20 20:15:50 2014
Media Recovery Applied until change 373573 --- the SCN to which the last application is Applied
Sun Apr 20 20:15:50 2014
MRP0: Media Recovery Complete: End-Of-REDO (PROD)
Resetting standby activation ID 257246883 (0xf5546a3)
Sun Apr 20 20:15:51 2014
MRP0: Background Media Recovery process shutdown (PROD) ---- media recovery process has been disabled
Sun Apr 20 20:16:21 2014
Alter database recover managed standby database cancel
Sun Apr 20 20:16:21 2014
ORA-16136 signalled during: alter database recover managed standby database cancel...

References:

Important configuration parameters of Oracle Data Guard

Configure Oracle 11g Data Guard based on the same host

Explore Oracle 11g elastic uard

Oracle Data Guard (RAC + DG) archive deletion policies and scripts

Role conversion for Oracle Data Guard

FAL gap in Oracle Data Guard logs

Oracle 11g Data Guard Error 16143 Heartbeat failed to connect to standby