scott@bjdb>conn /as sysdba
Connected.
sys@bjdb>alter system switch logfile;
System altered.

sys@bjdb>shutdown abort
ORACLE instance shut down.

sys@shdb>select name,database_role,switchover_status from v$database;
NAME DATABASE_ROLE SWITCHOVER_STATUS
--------- ---------------- --------------------
TESTDB12 PHYSICAL STANDBY NOT ALLOWED
可以看到此時備庫處于無法切換狀態

sys@shdb>alter database commit to switchover to primary;


alert_log:（告警日志）
Fatal NI connect error 12514, connecting to:
 (DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=shsrv)(PORT=1521)))(CONNECT_DATA=(SERVICE_NAME=shdb)(CID=(PROGRAM=oracle)(HOST=bjsrv)(USER=oracle))))
 VERSION INFORMATION:
 TNS for Linux: Version 11.2.0.3.0 - Production
 TCP/IP NT Protocol Adapter for Linux: Version 11.2.0.3.0 - Production
 Time: 04-MAR-2015 21:25:13
 Tracing not turned on.
 Tns error struct:
 ns main err code: 12564
 
TNS-12564: TNS:connection refused
 ns secondary err code: 0
 nt main err code: 0
 nt secondary err code: 0
 nt OS err code: 0
Error 12514 received logging on to the standby
FAL[client, MRP0]: Error 12514 connecting to shdb for fetching gap sequence
Wed Mar 04 21:26:00 2015
alter database commit to switchover to primary
ALTER DATABASE SWITCHOVER TO PRIMARY (TestDB12)
Maximum wait for role transition is 15 minutes.
Switchover: Media recovery is still active
Database not available for switchover
 End-Of-REDO archived log file has not been recovered
Database not available for switchover
 End-Of-REDO archived log file has not been recovered
Database not available for switchover

sys@shdb>ALTER DATABASE RECOVER managed standby database finish;

ALTER DATABASE RECOVER managed standby database finish 
Terminal Recovery: request posted (TestDB12)
Wed Mar 04 21:34:34 2015
Begin: Standby Redo Logfile archival
End: Standby Redo Logfile archival
Terminal Recovery timestamp is '03/04/2015 21:34:34'
Terminal Recovery: applying standby redo logs.
Terminal Recovery: thread 1 seq# 34 redo required
Media Recovery Waiting for thread 1 sequence 34
Terminal Recovery: End-Of-Redo log allocation
Terminal Recovery: standby redo logfile 4 created '/dsk4/arch_bj/arch_1_0_820054583.log'
This standby redo logfile is being created as part of the
failover operation. This standby redo logfile should be
deleted after the switchover to primary operation completes.
Media Recovery Log /dsk4/arch_bj/arch_1_0_820054583.log
Terminal Recovery: log 4 reserved for thread 1 sequence 34
Recovery of Online Redo Log: Thread 1 Group 4 Seq 34 Reading mem 0
 Mem# 0: /dsk4/arch_bj/arch_1_0_820054583.log
Identified End-Of-Redo (failover) for thread 1 sequence 34 at SCN 0xffff.ffffffff
Incomplete Recovery applied until change 1234252 time 03/04/2015 21:23:43
MRP0: Media Recovery Complete (TestDB12)
Terminal Recovery: successful completion
Wed Mar 04 21:34:35 2015
ARCH: Archival stopped, error occurred. Will continue retrying
ORACLE Instance TestDB12 - Archival Error
ORA-16014: log 4 sequence# 34 not archived, no available destinations
ORA-00312: online log 4 thread 1: '/dsk4/arch_bj/arch_1_0_820054583.log'
Forcing ARSCN to IRSCN for TR 0:1234252
Attempt to set limbo arscn 0:1234252 irscn 0:1234252 
Resetting standby activation ID 2865247982 (0xaac836ee)
MRP0: Background Media Recovery process shutdown (TestDB12)
Terminal Recovery: completion detected (TestDB12)
Completed: ALTER DATABASE RECOVER managed standby database finish

sys@shdb>select status from v$instance;
STATUS
------------
OPEN
sys@shdb>select name,database_role,switchover_status from v$database;
NAME DATABASE_ROLE SWITCHOVER_STATUS
--------- ---------------- --------------------
TESTDB12 PHYSICAL STANDBY TO PRIMARY

sys@shdb>alter database commit to switchover to primary;
Database altered.

sys@shdb>alter database open;
Database altered.

告警日志：
alter database commit to switchover to primary
ALTER DATABASE SWITCHOVER TO PRIMARY (TestDB12)
Maximum wait for role transition is 15 minutes.
All dispatchers and shared servers shutdown
CLOSE: killing server sessions.
CLOSE: all sessions shutdown successfully.
Wed Mar 04 21:35:47 2015
SMON: disabling cache recovery
Backup controlfile written to trace file /u01/app/oracle/diag/rdbms/bjdb/TestDB12/trace/TestDB12_ora_3146.trc
Standby terminal recovery start SCN: 1234251
RESETLOGS after incomplete recovery UNTIL CHANGE 1234252
Online log /dsk2/oradata/bjdb/redo01b.log: Thread 1 Group 1 was previously cleared
Online log /dsk1/oradata/bjdb/redo01a.log: Thread 1 Group 1 was previously cleared
Online log /dsk2/oradata/bjdb/redo02b.log: Thread 1 Group 2 was previously cleared
Online log /dsk1/oradata/bjdb/redo02a.log: Thread 1 Group 2 was previously cleared
Online log /dsk2/oradata/bjdb/redo03b.log: Thread 1 Group 3 was previously cleared
Online log /dsk1/oradata/bjdb/redo03a.log: Thread 1 Group 3 was previously cleared
Standby became primary SCN: 1234250
Wed Mar 04 21:35:47 2015
Setting recovery target incarnation to 3
AUDIT_TRAIL initialization parameter is changed back to its original value as specified in the parameter file.
Switchover: Complete - Database mounted as primary
Completed: alter database commit to switchover to primary

sys@bjdb>startup
ORACLE instance started.
Total System Global Area 442601472 bytes
Fixed Size 2229184 bytes
Variable Size 281021504 bytes
Database Buffers 155189248 bytes
Redo Buffers 4161536 bytes
Database mounted.
Database opened.

sys@bjdb>select name,database_role,switchover_status from v$database;
NAME DATABASE_ROLE SWITCHOVER_STATUS
--------- ---------------- --------------------
TESTDB12 PRIMARY FAILED DESTINATION

sys@bjdb>select name,database_role from v$database;