Required 5 background processes in oracle database

Introduce 5 required background processes in oracle database

SMON

SMON is the abbreviation of System Monitor. If Oracle Instance runs with error, the information in SGA, which hasn’t been written into the disk, will lose permanently. There are many reasons may cause the failure of the Oracle Instance. For instance, operating system crash will cause the Oracle Instance failure. When Oracle Instance failed, if re-open the database, the background process SMON automatically performs instance recovery operations.

 

PMON

PMON is the abbreviation of Process Monitor. When you cancel the current transaction, or release the lock and the process of occupation after the release of other resources, the PMON process will clear the failure process.

 

DBWR

DBWR is the abbreviation of Database Writer. The server process records all the changes and data in the buffer.DBWR write the dirty data generated in the Database Storage Buffer into the Data File to ensure that the Database Storage Buffer has enough free size. The dirty data is being used but hasn’t been written into the Data File.

 

LGWR

LGWR is the abbreviation of Log Writer. It is used to write the Redo Log Storage Buffer data into the Redo Log File.

CKPT

CKPT is the abbreviation of Checkpoint.  CKPT is used to synchronize the database files. It can write the log file into the database.