background processes

Here’s a list of background processes:

* SMON
The System Monitor carries out a crash recovery when a crashed insance is started up again. It also cleans temporary segments.
* PMON
The Process Monitor checks if a user process fails and if so, does all cleaning up of resources that the user process has aquired.
* DBWR
The Database Writer writes dirty blocks from the database buffer to the datafiles. How many DBWn Processes are started is determined by the initialization parameter DB_WRITER_PROCESSES. DBWR also writes the actual SCN with the Block.
* LGWR
The Log Writer writes the redo log buffer from the SGA to the online redo log file.
* MMAN
The memory manager
* MRP
Managed recovery process: the process that applies archived redo log to the standby database.
* RFS
The remote file server process on the standby database receives archived redo logs from the primary database.
* RECO
The Distributed Transaction Recovery Process finds pending (distributed) transaction and resolves them.
* CKPT
The Checkpoint Process reqularly initiates a checkpoint which uses DBWR to write all dirty blocks back to the datafiles, thus synchronizing the database. Since a Checkpoint records the current SCN, in a recovery only redo records with a SCN higher than that of the last checkpoint need to be applied.
* ARCH
The Archiver Process archives redo log files if ARCHIVELOG is enabled.
* Dnnn
The Dispatcher Process is used in a shared server environment.
* Snnn
The Shared Server Process is used in a shared server environment.
* LMON
The lock manager.
* LMD0
* QMNn
AQ Time Manager
* TRWR
Trace writer
* WMON
The wakeup monitor process.
* LCKnnn
Inter-instance locking process.
* SNPnnn
The snapshot process.
* MMON
New background process in Oracle 10g.
* DMON
The Data Guard Broker process.
* SNP
The snapshot process.

Background processes have v$session.type = ‘BACKGROUND’

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