oracle dg 状态检查

先检查备库的归档日志同步情况 

SELECT NAME,applied FROM v$archived_log; 

alter database recover managed standby database cancel;

select thread#,sequence#,standby_dest,archived,applied,status from v$archived_log order by 1,2;

alter database recover managed standby database using current logfile disconnect from session;

.在备库 查看gap

1.      select * from v$archive_gap;

ALTER  DATABASE RECOVER MANAGED STANDBY  DATABASE DISCONNECT FROM SESSION;

查看主库的基本信息：

SYS@enmo1 hey~1->select open_mode,protection_mode,database_role,switchover_status from v$database;

OPEN_MODE            PROTECTION_MODE             DATABASE_ROLE         SWITCHOVER_STATUS
-------------------- ----------------------------- ------------------------ ------------------------
READ WRITE           MAXIMUM PERFORMANCE      PRIMARY                      TO STANDBY

查看备库的基本信息：

SYS@enmo2 hey~2->select open_mode,protection_mode,database_role,switchover_status from v$database;

OPEN_MODE                   PROTECTION_MODE             DATABASE_ROLE         SWITCHOVER_STATUS
------------------------- ----------------------------- ------------------------ ------------------------
READ ONLY WITH APPLY MAXIMUM PERFORMANCE      PHYSICAL STANDBY      NOT ALLOWED

备库应用日志保持和主库数据一致（如果不一致，执行如下语句应用日志）

SYS@enmo2 hey~2->recover managed standby database using current logfile disconnect from session;
Media recovery complete.

SYS@enmo2 hey~2->recover managed standby database cancel;
Media recovery complete.

主库切换到备库角色并查看切换之后的状态为RECOVERY NEEDED

SYS@enmo1 hey~1->alter database commit to switchover to physical standby with session shutdown;

Database altered.

SYS@enmo1 hey~1->shutdown abort;

ORACLE instance started.

Total System Global Area 830930944 bytes
Fixed Size 2257800 bytes
Variable Size 700451960 bytes
Database Buffers 121634816 bytes
Redo Buffers 6586368 bytes
Database mounted.
SYS@enmo1 hey~1->select switchover_status from v$database;

SWITCHOVER_STATUS
--------------------
RECOVERY NEEDED

切换应用日志，然后在查看切换状态为TO primary正常：

SYS@enmo1 hey~1->recover managed standby database using current logfile disconnect from session;
Media recovery complete.
SYS@enmo1 hey~1->select switchover_status from v$database;

SWITCHOVER_STATUS
--------------------
TO PRIMARY

备库切主库：

SYS@enmo2 hey~2->select open_mode,protection_mode,database_role,switchover_status from v$database;

OPEN_MODE PROTECTION_MODE DATABASE_ROLE SWITCHOVER_STATUS
-------------------- -------------------- ---------------- --------------------
MOUNTED MAXIMUM PERFORMANCE PHYSICAL STANDBY TO PRIMARY

SYS@enmo2 hey~2->alter database commit to switchover to primary with session shutdown;

Database altered.

SYS@enmo2 hey~2->alter database open;

Database altered.

SYS@enmo2 hey~2->select switchover_status,database_role from v$database;

SWITCHOVER_STATUS DATABASE_ROLE
-------------------- ----------------
FAILED DESTINATION PRIMARY

SYS@enmo2 hey~2->select open_mode,protection_mode,database_role from v$database;

OPEN_MODE PROTECTION_MODE DATABASE_ROLE
-------------------- -------------------- ----------------

READ WRITE MAXIMUM PERFORMANCE PRIMARY

二、备库不同步的问题检查方法

1、检查主备两边的序号
select max(sequence#) from v$log;   ---检查发现一致

2、备库执行，查看是否有数据未应用
select name,SEQUENCE#,APPLIED from v$archived_log order by sequence#;

select SEQUENCE#,FIRST_TIME,NEXT_TIME ,APPLIED from v$archived_log order by 1;

3、检查备库是否开启实时应用
select recovery_mode from v$archive_dest_status where dest_id=2;

4、检查备库状态
select switchover_status from v$database; --发现状态not allowed 

3、看看进程MRP是否存在
 ps aux|grep mrp      --发现进程不存在

4、如果不存在执行以下：
alter database recover managed standby database using current logfile disconnect;

alter database recover managed standby database disconnect from session;  --后台执行

alter database recover managed standby database --前台执行，执行这个可以看到报错的情况

如果有报错，查看alert日志和log.xml日志 

5、验证是否正常
select process,status from v$managed_standby;
select process,status,sequence# from v$managed_standby;

如果看到mrp0正常

6、以上步骤处理好后，如果数据还不正常，接着处理

关闭备库，接着处理：
把主库上 undotbs01.dbf 文件，物理的重拷到备库机上以前undotbs01.dbf 所在目录下；

$scp /data/oracle/oradata/voip/undotbs01.dbf   192.168.122.204:/data/oracle/oradata/voip

再在主库上重新生成一个standby control file ，拷到备库机上相应目录下，

alter database create standby controlfile as '/data/oracle/oradata/voip/qyqdg01.ctl'

$scp /data/oracle/oradata/voip/qyqdg01.ctl   192.168.122.204:/data/oracle/oradata/voip
$ mv qyqdg01.ctl  control01.ctl
$ cp control01.ctl /data/oracle/flash_recovery_area/qyq/
$cd /data/oracle/flash_recovery_area/qyq/
$ mv control01.ctl  control02.ctl

接着
STARTUP NOMOUNT;
ALTER DATABASE MOUNT STANDBY DATABASE;
ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION;

--------------------------------------
session恢复完成后，重启打开备库；

alter database open read only;