文档课题：测试Kill MMON进程对数据库的影响.
数据库：oracle 11.2.0.4
1、异常模拟
[oracle@racogg:~]$ ps -ef | grep mmon | grep -v grep 
oracle    13879      1  0 Jan06 ?        00:00:11 ora_mmon_orcl
[oracle@racogg:~]$ ps -ef | grep ora_smon | grep -v grep 
oracle    13875      1  0 Jan06 ?        00:00:05 ora_smon_orcl
[oracle@racogg:~]$ kill -9 13879
[oracle@racogg:~]$ ps -ef|grep ora_smon
oracle    13875      1  0 Jan06 ?        00:00:05 ora_smon_orcl

说明：如上kill mmon进程后，数据库不会出现down机的异常,但无法自动生成AWR快照.

2、开启MMON进程
说明：kill mmon进程后并不会自动开启，虽然重启数据库能实现重启mmon进程，但在生产环境不太现实.
以下演示在不关闭数据库的情况下重启mmon进程,生产环境需选择在业务空闲时启动restricted模式，然后立即禁用.
2.1、启用restricted模式
[oracle@racogg:~]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.4.0 Production on Sun Jan 7 14:46:06 2024

Copyright (c) 1982, 2013, Oracle.  All rights reserved.


Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

sys@ORCL 2024-01-07 14:46:06> alter system enable restricted session;

System altered.

sys@ORCL 2024-01-07 14:46:23> exit

Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

2.2、启用restricted模式后的影响
[oracle@racogg:~]$ sqlplus sys/oracle_4U@192.168.133.196:1521/orcl as sysdba

SQL*Plus: Release 11.2.0.4.0 Production on Sun Jan 7 14:47:25 2024

Copyright (c) 1982, 2013, Oracle.  All rights reserved.

ERROR:
ORA-12526: TNS:listener: all appropriate instances are in restricted mode


Enter user-name: 

[oracle@racogg:~]$ sqlplus sys/oracle_4U@orcl as sysdba

SQL*Plus: Release 11.2.0.4.0 Production on Sun Jan 7 14:48:52 2024

Copyright (c) 1982, 2013, Oracle.  All rights reserved.

ERROR:
ORA-12526: TNS:listener: all appropriate instances are in restricted mode


Enter user-name: 

[oracle@racogg:~]$ ps -ef | grep mmon | grep -v grep
oracle    74927      1  0 14:46 ?        00:00:00 ora_mmon_orcl

小结：如上所示，启用restricted模式后无法通过简易&tnsnames的方式连接数据库，但mmon进程被成功开启.

2.3、关闭restricted模式
[oracle@racogg:~]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.4.0 Production on Sun Jan 7 14:49:10 2024

Copyright (c) 1982, 2013, Oracle.  All rights reserved.


Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

sys@ORCL 2024-01-07 14:49:10> alter system disable restricted session;

System altered.

sys@ORCL 2024-01-07 14:50:11> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

小结：通过本地服务器连接数据库，关闭restricted模式.

2.4、关闭restricted模式后的影响
[oracle@racogg:~]$ sqlplus sys/oracle_4U@orcl as sysdba

SQL*Plus: Release 11.2.0.4.0 Production on Sun Jan 7 14:50:20 2024

Copyright (c) 1982, 2013, Oracle.  All rights reserved.


Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

sys@ORCL 2024-01-07 14:50:20> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
[oracle@racogg:~]$ sqlplus sys/oracle_4U@192.168.133.196:1521/orcl as sysdba

SQL*Plus: Release 11.2.0.4.0 Production on Sun Jan 7 14:50:25 2024

Copyright (c) 1982, 2013, Oracle.  All rights reserved.


Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

sys@ORCL 2024-01-07 14:50:11> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

[oracle@racogg:~]$ ps -ef | grep mmon | grep -v grep
oracle    74927      1  0 14:46 ?        00:00:00 ora_mmon_orcl

小结：关闭restricted模式后，简易&tnsnames方式成功连接数据库.