List of background Processes in Oracle Database 12c

Acronym

	Process Name	Description	Required for basic DB operation	Started by default	New in this release
ABMR	Auto BMR Background Process	Coordinates execution of tasks such as filtering duplicate block media recovery requests and performing flood control.	No	No	No
APnn	Logical Standby / Streams Apply Process Coordinator Process	Obtains transactions from the reader server and passes them to apply servers	No	No	No
ARC 0..t	Archiver Process (30 possible)	Copies the redo log files to archival storage when they are full or an online redo log switch occurs	No	No	No
BMRn	Automatic Block Media Recovery Slave Pool Process	Fetches blocks from a real-time readable standby database	No	No	No
BW nn	Database Writer Process (20 possible)	Writes modified blocks from the database buffer cache to the data files. The names of the 37th through 100th Database Writer Processes are BW36-BW99. See DBWn for more information on these processes.	Yes	Yes	Yes
CJQ0	Job Queue Coordinator Process	Spawns slave processes (Jnnn) to execute jobs in the queue.	No	Yes	No
CKPT	Checkpoint Process	Signals DBWn at checkpoints and updates all the data files and control files of the database to indicate the most recent checkpoint	Yes	Yes	No
CPnn	Database Capture Process	Captures database changes from the redo log by using the infrastructure of LogMiner.	No	No	No
CSnn	Streams Propagation Sender Process	Sends LCRs to a propagation receiver.	No	No	No
CSnn	I/O Calibration Process	Issues I/Os to storage as part of storage calibration. There is one slave process per CPU on each node of the database.	Yes	Yes	No
CTWR	Change Tracking Writer Process	Tracks changed data blocks as part of the Recovery Manager block change tracking feature	No	No	No
DBRM	Database Resource Manager Process	Sets resource plans and performs other Resource Manager tasks.	No	Yes	No
DBW 0..j	Database Writer Process	Writes modified blocks from the database buffer cache to the data files. There can be 1 to 100 Database Writer Processes. The names of the first 36 Database Writer Processes are DBW0-DBW9 and DBWa-DBWz. The names of the 37th through 100th Database Writer Processes are BW36-BW99.	Yes	Yes	No
DIA0	Diagnostic Process 0 (although 10 possible, only 0 is currently used)	Responsible for hang detection and deadlock resolution. Triggers DIAG to perform diagnostic tasks.	Yes	Yes	No
DIAG	Diagnostic Capture Process	Performs diagnostic dumps and executes global oradebug commands.	Yes	Yes	No
DMnn	Data Pump Master Process	Coordinates the Data Pump job tasks performed by Data Pump worker processes and handles client interactions.	No	No	No
Dnnn	Dispatcher Process	In a Shared Server configuration, dispatchers place connection requests in a connection request queue.	No	Yes	No
DWnn	Data Pump Worker Process	Performs Data Pump tasks as assigned by the Data Pump Master Process.	No	No	No
EMNC	EMON Coordinator Process	Coordinates the event management and notification activity in the database, including Streams Event Notifications, Continuous Query Notifications, and Fast Application Notifications. Spawns Ennn processes.	No	No	No
Ennn	EMON Slave Process	Performs database event management and notifications.	No	No	No
FBDA	Flashback Data Archiver Process	Archives historical rows for tracked tables into flashback data archives and manages archive space, organization, and retention	No	No	No
FMON	File Mapping Monitor Process	Spawns FMPUTL, an external non-Oracle Database process that communicates with the mapping libraries provided by storage vendors. Responsible for managing the mapping information.	No	No	No
GEN0	General Task Execution Process	Performs required tasks including SQL and DML.	Yes	Yes	No
Innn	Disk and Tape I/O Slave Process	Serves as an I/O slave process spawned on behalf of DBWR, LGWR, or an RMAN backup session.	No	No	No
Jnnn	Job Queue Slave Processes	Processes jobs in the queue. Spawned by CJQ0.	No	Yes	No
LGn	Log Writer Slave	On multiprocessor systems, LGWR creates slave processes to improve the performance of writing to the redo log. LGWR slaves are not used when there is a SYNC standby destination.	No	No	Yes
LGWR	Log Writer Process	Writes the log buffer out to the redo logs.	Yes	Yes	No
Lnnn	Pooled Server Process	Handles client requests in Database Resident Connection Pooling.	No	No	No
LREG	Listener Registration Process	LREG notifies the listeners about instances, services, handlers, and endpoint.	Yes	Yes	Yes
MMAN	Memory Manager Process	Serves as the SGA Memory Broker and coordinates the sizing of the memory components.	No	Yes	No
MMNL	Manageability Monitor Lite Process	Performs frequent and lightweight manageability-related tasks, such as session history capture and metrics computation.	No	Yes	No
MMON	Manageability Monitor Process	Collects statistics for the Automatic Workload Repository.	No	Yes	No
Mnnn	MMON Slave Process	Performs manageability tasks on behalf of MMON.	No	No	No
MSnn	LogMiner Worker Process	Reads redo log files and translates and assembles into transactions.	No	No	No
Nnnn	Connection Broker Process	Monitors idle connections and hands off active connections in Database Resident Connection Pooling	No	No	No
OFSD	Oracle File Server Background Process	This background process listens for new file system requests, both management (like mount, unmount, and export) and I/O requests, and executes them using Oracle threads.	Yes	Yes	No
PMON	Process Monitor	Recovers failed process resources. If Shared Server architecture is used, PMON monitors and restarts any failed dispatcher or server processes.	Yes	Yes	No
Pnnn	Parallel Query Slave Process	Started and stopped as needed to participate in parallel query operations.	No	No	No
PRnn	Parallel Recovery Process	Performs tasks assigned by the coordinator process performing parallel recovery	No	No	No
PSP0	Process Spawner Process	Starts and stops Oracle processes. Reduces workload of RBAL by starting / stopping ASM rebalance slaves.	No	Yes	No
RCBG	Result Cache Background Process	Supports SQL query and PL/SQL function result caches.	No	No	No
RECO	Recoverer Process	Resolves failures involving distributed transactions.	No	Yes	No
RM	RAT Masking Slave Process	This background process is used with Data Masking and Real Application Testing.	No	Yes	Yes
RPnn	Capture Processing Worker Process	Processes a set of workload capture files.	No	No	No
RPOP	Instant Recovery Repopulation Daemon	Responsible for re-creating and/or repopulating data files from snapshot files and backup files. The RPOP process is responsible for re-creating and repopulating data files from snapshots files. It works with the instant recovery feature to ensure immediate data file access. The local instance has immediate access to the remote snapshot file's data, while repopulation of the recovered primary data files happens concurrently. Any changes in the data are managed between the instance's DBW processes and RPOP to ensure the latest copy of the data is returned to the user.	No	No	Yes
RVWR	Recovery Writer Process	Writes flashback data to flashback database logs in the flash recovery area.	No	No	No
SAnn	SG Allocator	A small fraction of SGA is allocated during instance startup. The SAnn process allocates the rest of SGA in small chunks. The process exits upon completion of SGA allocation.	No	Yes	Yes
SMCO	Space Management Coordinator Process	Coordinates the execution of various space management related tasks, such as proactive space allocation and space reclamation.	No	Yes	No
SMON	System Monitor Process	Performs critical tasks such as instance recovery and dead transaction recovery, and maintenance tasks such as temporary space reclamation, data dictionary cleanup, and undo tablespace management	Yes	Yes	No
Snnn	Shared Server Process	In a Shared Server configuration, shared servers check a connection request queue (populated by dispatchers) and services the connection requests.	No	Yes	No
VKRM	Virtual Scheduler for Resource Manager Process	Serves as centralized scheduler for Resource Manager activity.	No	Yes	No
VKTM	Virtual Keeper of Time Process	Responsible for providing a wall-clock time (updated every second) and reference-time counter (updated every 20ms and available only when running at elevated priority).	Yes	Yes	No
Wnnn	Space Management Slave Process	These are slave processes spawned by SMCO to execute space management tasks.	No	Yes	No