Oracle Architecture and Backup (12) Bg-smon

One what is the Smon process

The systemmonitor performs recovery when a failed instance starts up again. In a oraclereal application clusters database, the Smon process of one instance Canperform instance for other Stances that have failed. Smon Alsocleans up temporary segments this are no longer in use and recovers deadtransactions skipped during system Failur E and instance recovery because offile-read or offline errors. These transactions are eventually recovered Bysmon then the tablespace or file is brought back online.

Role:

Instance Recovery

Roll forward changes in all redo logs

Open a database to enable users to access

Rollback transactions that are not committed

The space to engage the free (coalesce every three secons)

Free temporary tablespace (Deal located)

Example of two operations

 sql> startup force;  
      
ORACLE instance started. Total System Global area 838860800 bytes Fixed Size 1222192 bytes Variable Size 775948752 bytes Da  
Tabase buffers 58720256 bytes Redo buffers the 2969600 Database bytes.  
Database opened.  
sql> startup force Mount;  
      
ORACLE instance started. Total System Global area 838860800 bytes Fixed Size 1222192 bytes Variable Size 775948752 bytes Da  
Tabase buffers 58720256 bytes Redo buffers the 2969600 Database bytes.  
-This problem occurs: Close the database and restart sql> ALTER DATABASE archivelog;  
      
ALTER DATABASE Archivelog * ERROR at line 1:ora-00265:instance recovery required, cannot set Archivelog mode  
sql> shutdown immediate;  
Ora-01109:database not open database dismounted.  
ORACLE instance shut down.  
Sql> startup;  
      
ORACLE instance started. Total System Global area 838860800 bytes Fixed Size 1222192 bytes Variable size 775948752 bytes Database buffers 58720256 bytes Redo Buffer  
s 2969600 bytes Database mounted.  
Database opened.  
sql> shutdown Mount;  
Sp2-0717:illegal SHUTDOWN option sql> SHUTDOWN immediate;  
Database closed.  
Database dismounted.  
ORACLE instance shut down.  
sql> startup Mount;  
      
ORACLE instance started. Total System Global area 838860800 bytes Fixed Size 1222192 bytes Variable Size 775948752 bytes Da  
      
Tabase buffers 58720256 bytes Redo buffers the 2969600 Database bytes.  
      
sql> ALTER DATABASE Noarchivelog;  
      
Database altered.  
      
sql> ALTER DATABASE open; Database altered. 

Three summary

1. Smon: System monitoring process, static registration monitoring

2.SMON function: Instance recovery, joining the free space (coalesceevery three secons),

Free temporary tablespace (Deal located)