DG - physical standby switchover切换过程

一.切换前检查
1.检查备库已经全部接收到主库的redo
如果是最大可用性、最大保护性模式，可以在primary端查看v$archive_dest_status，确认是否所有的redo已经传送到备库
#在主库执行

SQL> select db_unique_name,protection_mode,synchronization_status,synchronized from v$archive_dest_status;

DB_UNIQUE_NAME                 PROTECTION_MODE      SYNCHRONIZATION_STATUS SYN
------------------------------ -------------------- ---------------------- ---
NONE                           MAXIMUM PERFORMANCE  CHECK CONFIGURATION    NO
dgs                            MAXIMUM PERFORMANCE  DESTINATION HAS A GAP  NO

SQL>

可以看出主备未同步且是最大性能保护模式，还要执行更多检查操作(如果是最大可用性、最大保护性模式但未同步，同样需要执行更多检查操作)：
#在主库执行

SQL> select thread#,sequence#,status from v$log;

   THREAD#  SEQUENCE# STATUS
---------- ---------- ----------------
         1         46 INACTIVE
         1         47 CURRENT
         1         45 INACTIVE

SQL>

#在备库执行

SQL> select client_process,process,sequence#,status from v$managed_standby;

CLIENT_P PROCESS    SEQUENCE# STATUS
-------- --------- ---------- ------------
ARCH     ARCH              46 CLOSING
ARCH     ARCH               0 CONNECTED
ARCH     ARCH               0 CONNECTED
ARCH     ARCH               0 CONNECTED
ARCH     ARCH              44 CLOSING
ARCH     RFS                0 IDLE
UNKNOWN  RFS                0 IDLE
UNKNOWN  RFS                0 IDLE
LGWR     RFS               47 IDLE
N/A      MRP0              47 WAIT_FOR_LOG

10 rows selected.

SQL>

从结果可以看出，当前主库发送来的sequence是47

2.检查备库已经将所有redo应用到备库
2.1 physical standby环境

SQL> select client_process,process,sequence#,status from v$managed_standby;

CLIENT_P PROCESS    SEQUENCE# STATUS
-------- --------- ---------- ------------
...
N/A      MRP0              48 WAIT_FOR_LOG
...
10 rows selected.

SQL>

如果MRP0的状态是"wait_for_gap",则不能进行switchover。"wait_for_log"表示要么没有开启实时应用、要么开启了delay设置。如果是设置了delay，要停止redo apply，使用nodelay重启redo apply，否则无法switchover。

2.2 logical standby环境

SQL> select applied_scn, latest_scn, mining_scn from v$logstdby_progress;

SQL> select status from v$logstdby_process where type='READER';

3.停掉主库上的job、rman操作等

SQL> select process, operation, r.status, mbytes_processed pct, s.status from v$rman_status r, v$session s where r.sid=s.sid;

二、正式切换

1.主库查看

SQL> SELECT SWITCHOVER_STATUS FROM V$DATABASE;

SWITCHOVER_STATUS
--------------------
TO STANDBY

SQL> SELECT PROGRAM, TYPE FROM V$SESSION WHERE TYPE='USER';

PROGRAM                                          TYPE
------------------------------------------------ ----------
sqlplus@dgp.example.com (TNS V1-V3)              USER

SQL>

2.备库查看

SQL> SELECT PROGRAM, TYPE FROM V$SESSION WHERE TYPE='USER';

PROGRAM                                          TYPE
------------------------------------------------ ----------
sqlplus@dgs.example.com (TNS V1-V3)              USER
oracle@dgp.example.com (TNS V1-V3)               USER
oracle@dgp.example.com (TNS V1-V3)               USER
oracle@dgp.example.com (TNS V1-V3)               USER
oracle@dgp.example.com (TNS V1-V3)               USER

SQL>

3.主库执行switchover操作

SQL> alter database commit to switchover to physical standby with session shutdown;

对应的主库alert日志内容：

Thu Apr 21 05:24:25 2016
alter database commit to switchover to physical standby with session shutdown
ALTER DATABASE COMMIT TO SWITCHOVER TO PHYSICAL STANDBY [Process Id: 2796] (dgp)
Waiting for all non-current ORLs to be archived...
All non-current ORLs have been archived.
Waiting for all FAL entries to be archived...
All FAL entries have been archived.
Waiting for potential Physical Standby switchover target to become synchronized...
Active, synchronized Physical Standby switchover target has been identified
Switchover End-Of-Redo Log thread 1 sequence 48 has been fixed
Switchover: Primary highest seen SCN set to 0x0.0x110542
ARCH: Noswitch archival of thread 1, sequence 48
ARCH: End-Of-Redo Branch archival of thread 1 sequence 48
ARCH: LGWR is actively archiving destination LOG_ARCHIVE_DEST_2
ARCH: Standby redo logfile selected for thread 1 sequence 48 for destination LOG_ARCHIVE_DEST_2
Archived Log entry 83 added for thread 1 sequence 48 ID 0x664ffa3a dest 1:
ARCH: Archiving is disabled due to current logfile archival
Primary will check for some target standby to have received alls redo
Final check for a synchronized target standby. Check will be made once.
LOG_ARCHIVE_DEST_2 is a potential Physical Standby switchover target
Active, synchronized target has been identified
Target has also received all redo
Backup controlfile written to trace file /p01/app/oracle/diag/rdbms/dgp/dgp/trace/dgp_ora_2796.trc
Clearing standby activation ID 1716517434 (0x664ffa3a)
The primary database controlfile was created using the
'MAXLOGFILES 16' clause.
There is space for up to 13 standby redo logfiles
Use the following SQL commands on the standby database to create
standby redo logfiles that match the primary database:
ALTER DATABASE ADD STANDBY LOGFILE 'srl1.f' SIZE 52428800;
ALTER DATABASE ADD STANDBY LOGFILE 'srl2.f' SIZE 52428800;
ALTER DATABASE ADD STANDBY LOGFILE 'srl3.f' SIZE 52428800;
ALTER DATABASE ADD STANDBY LOGFILE 'srl4.f' SIZE 52428800;
Archivelog for thread 1 sequence 48 required for standby recovery
Switchover: Primary controlfile converted to standby controlfile succesfully.
Switchover: Complete - Database shutdown required
USER (ospid: 2796): terminating the instance
Instance terminated by USER, pid = 2796
Completed: alter database commit to switchover to physical standby with session shutdown
Shutting down instance (abort)
License high water mark = 5
Thu Apr 21 05:24:28 2016
Instance shutdown complete

对应备库alert日志：

Thu Apr 21 05:24:24 2016
RFS[3]: Possible network disconnect with primary database
Thu Apr 21 05:24:27 2016
RFS[4]: Assigned to RFS process 2841
RFS[4]: Selected log 5 for thread 1 sequence 48 dbid 1716485690 branch 909194174
Thu Apr 21 05:24:27 2016
Archived Log entry 41 added for thread 1 sequence 48 ID 0x664ffa3a dest 1:
Thu Apr 21 05:24:27 2016
RFS[1]: Possible network disconnect with primary database
Thu Apr 21 05:24:27 2016
RFS[5]: Assigned to RFS process 2843
RFS[5]: Possible network disconnect with primary database
Thu Apr 21 05:24:27 2016
RFS[2]: Possible network disconnect with primary database
Thu Apr 21 05:24:28 2016
Media Recovery Log /s01/app/oracle/arch/1_48_909194174.dbf
Identified End-Of-Redo (switchover) for thread 1 sequence 48 at SCN 0x0.110542
Resetting standby activation ID 1716517434 (0x664ffa3a)
Media Recovery End-Of-Redo indicator encountered
Media Recovery Continuing
Media Recovery Waiting for thread 1 sequence 49

4.备库切换成主库

SQL> alter database commit to switchover to primary with session shutdown;

切换过程对应的alert日志：

Thu Apr 21 05:26:59 2016
ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY
WITH SESSION SHUTDOWN
ALTER DATABASE SWITCHOVER TO PRIMARY (dgs)
Maximum wait for role transition is 15 minutes.
Switchover: Media recovery is still active
Role Change: Canceling MRP - no more redo to apply
Thu Apr 21 05:27:01 2016
MRP0: Background Media Recovery cancelled with status 16037
Errors in file /s01/app/oracle/diag/rdbms/dgs/dgs/trace/dgs_mrp0_2377.trc:
ORA-16037: user requested cancel of managed recovery operation
Recovery interrupted!
MRP0: Background Media Recovery process shutdown (dgs)
Role Change: Canceled MRP
All dispatchers and shared servers shutdown
CLOSE: killing server sessions.
CLOSE: all sessions shutdown successfully.
Thu Apr 21 05:27:02 2016
SMON: disabling cache recovery
Backup controlfile written to trace file /s01/app/oracle/diag/rdbms/dgs/dgs/trace/dgs_ora_2755.trc
SwitchOver after complete recovery through change 1115458
Online log /s01/app/oracle/oradata/dgs/redo01.log: Thread 1 Group 1 was previously cleared
Online log /s01/app/oracle/oradata/dgs/redo02.log: Thread 1 Group 2 was previously cleared
Online log /s01/app/oracle/oradata/dgs/redo03.log: Thread 1 Group 3 was previously cleared
Standby became primary SCN: 1115456
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
WITH SESSION SHUTDOWN

5.打开新主库

SQL> alter database open;

对应alert日志：

Thu Apr 21 05:27:52 2016
idle dispatcher 'D000' terminated, pid = (17, 1)
Thu Apr 21 05:28:01 2016
ARC1: Becoming the 'no SRL' ARCH
Thu Apr 21 05:28:39 2016
alter database open
Thu Apr 21 05:28:39 2016
Assigning activation ID 1717040723 (0x6657f653)
Destination LOG_ARCHIVE_DEST_2 is UNSYNCHRONIZED
Thread 1 advanced to log sequence 50 (thread open)
Thread 1 opened at log sequence 50
  Current log# 2 seq# 50 mem# 0: /s01/app/oracle/oradata/dgs/redo02.log
Successful open of redo thread 1
MTTR advisory is disabled because FAST_START_MTTR_TARGET is not set
Thu Apr 21 05:28:39 2016
SMON: enabling cache recovery
Thu Apr 21 05:28:39 2016

***********************************************************************

Fatal NI connect error 12514, connecting to:
 (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=dgp.example.com)(PORT=1521))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=dgp)(CID=(PROGRAM=oracle)(HOST=dgs.example.com)(USER=oracle))))

  VERSION INFORMATION:
        TNS for Linux: Version 11.2.0.4.0 - Production
        TCP/IP NT Protocol Adapter for Linux: Version 11.2.0.4.0 - Production
  Time: 21-APR-2016 05:28:39
  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

***********************************************************************

6.打开新的备库

SQL> shutdown immediate
SQL> startup mount
SQL> alter database recover managed standby database using current logfile disconnect;

7.新的主库查看

SQL> select open_mode,PROTECTION_MODE,PROTECTION_LEVEL, DATABASE_ROLE   from v$database;

OPEN_MODE            PROTECTION_MODE      PROTECTION_LEVEL     DATABASE_ROLE
-------------------- -------------------- -------------------- ----------------
READ WRITE           MAXIMUM PERFORMANCE  MAXIMUM PERFORMANCE  PRIMARY

SQL>

8.新的备库查看

SQL> select open_mode,PROTECTION_MODE,PROTECTION_LEVEL, DATABASE_ROLE   from v$database;

OPEN_MODE            PROTECTION_MODE      PROTECTION_LEVEL     DATABASE_ROLE
-------------------- -------------------- -------------------- ----------------
MOUNTED              MAXIMUM PERFORMANCE  MAXIMUM PERFORMANCE  PHYSICAL STANDBY

SQL>