List of New Background Processes in Oracle 12c

Name Expanded Name Short Description Long Description External Properties
AQPC AQ Process Coordinator Per instance AQ global coordinator AQPC is responsible for performing administrative tasks for AQ Master Class Processes including commands like starting, stopping, and other administrative tasks. This process is automatically started on instance startup. Database instances Advanced Queueing
ARSn ASM Recovery Slave Process Recovers ASM transactional operations The ASM RBAL background process coordinates and spawns one or more of these slave processes to recover aborted ASM transactional operations. These processes run only in the Oracle ASM instance.Possible processes are ARS0-ARS9. Oracle ASM instances
BWnn Database Writer Process Writes modified blocks from the database buffer cache to the data files See the Long Description for the DBWn process in this table for more information about the BWnn process. Database instances
FENC Fence Monitor Process Processes fence requests for RDBMS instances which are using Oracle ASM instances CSS monitors RDBMS instances which are connected to the Oracle ASM instance and constantly doing I/Os. When the RDBMS instance terminates due to a failure, all the outstanding I/O’s from the RDBMS instance should be drained and any new I/O’s rejected. FENC receives and processes the fence request from CSSD. Oracle ASM instances
IPC0 IPC Service Background Process Common background server for basic messaging and RDMA primitives based on IPC (Inter-process communication) methods. IPC0 handles very high rates of incoming connect requests, as well as, completing reconfigurations to support basic messaging and RDMA primitives over several transports such as UDP, RDS, InfiniBand and RC. Oracle RAC
LDDn Global Enqueue Service Daemon Helper Slave Helps the LMDn processes with various tasks LDDn processes are slave processes spawned on demand by LMDn processes. They are spawned to help the dedicated LMDn processes with various tasks when certain workloads start creating performance bottlenecks. These slave processes are transient as they are started on demand and they can be shutdown when no longer needed. There can be up to 36 of these slave processes (LDD0-LDDz). Database instances, Oracle ASM instances, Oracle RAC
LGnn Log Writer Worker Writes redo log On multiprocessor systems, LGWR creates worker processes to improve the performance of writing to the redo log. LGWR workers are not used when there is a SYNC standby destination. Possible processes include LG00-LG99. Database instances
LREG Listener Registration Process Registers the instance with the listeners LREG notifies the listeners about instances, services, handlers, and endpoint. Database instances, Oracle ASM instances, Oracle RAC
OFSD Oracle File Server Background Process Serves file system requests submitted to an Oracle instance 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. Database instances, Oracle RAC
QMnn AQ Master Class Process Per instance per AQ Master Class Process Each of this type of process represents a single class of work item such as AQ notification, queue monitors, and cross process. Database instances Advanced Queueing
RM RAT Masking Slave Process Extracts and masks bind values from workloads like SQL tuning sets and DB Replay capture files This background process is used with Data Masking and Real Application Testing. Database instances
RMON Rolling Migration Monitor Process Manages the rolling migration procedure for an Oracle ASM cluster The RMON process is spawned on demand to run the protocol for transitioning an ASM cluster in and out of rolling migration mode. Oracle ASM instance, Oracle RAC
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. Database instances
SAnn SGA Allocator Allocates SGA 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.The possible processes are SA00 – SAzz. Database instances
SCCn ASM Disk Scrubbing Slave Check Process Performs Oracle ASM disk scrubbing check operation SCCn acts as a slave process for SCRB and performs the checking operations. The possible processes are SCC0-SCC9. Oracle ASM instances
SCRB ASM Disk Scrubbing Master Process Coordinates Oracle ASM disk scrubbing operations SCRB runs in an Oracle ASM instance and coordinates Oracle ASM disk scrubbing operations. Oracle ASM instances
SCRn ASM Disk Scrubbing Slave Repair Process Performs Oracle ASM disk scrubbing repair operation SCRn acts as a slave process for SCRB and performs the repairing operations. The possible processes are SCR0-SCR9. Oracle ASM instances
SCVn ASM Disk Scrubbing Slave Verify Process Performs Oracle ASM disk scrubbing verify operation SCVn acts as a slave process for SCRB and performs the verifying operations. The possible processes are SCV0-SCV9. Oracle ASM instances
VUBG Volume drive Umbilicus Background Relays messages between Oracle ASM instance and Oracle ASM Proxy instance that is used by ADVM (for ACFS) Oracle ASM instances, Oracle ASM Proxy instances

But that is not all. One has actually been renamed all together and two have been enabled for multi-processing indicated by the “n” at the back of the name in the list below:

Name (12c) Previous name (11gR2) Expanded Name Short Description Long Description External Properties
LCKn LCK0 Lock Process Manages global enqueue requests and cross-instance broadcasts The process handles all requests for resources other than data blocks. For examples, LCKn manages library and row cache requests. Possible processes are LCK0 and LCK1. Database instances, Oracle ASM instances, Oracle RAC
LMDn LMD0 Global Enqueue Service Daemon Process Manages incoming remote resource requests from other instances LMDn processes enqueue resources managed under Global Enqueue Service. In particular, they process incoming enqueue request messages and control access to global enqueues. They also perform distributed deadlock detections. There can be up to 36 of these processes (LMD0-LMDz). Database instances, Oracle ASM instances, Oracle RAC
TTnn NSAn Redo Transport Slave Process Ships redo from current online and standby redo logs to remote standby destinations configured for ASYNC transport TTnn can run as multiple processes, where nn is 00 to ZZ.See Also: Oracle Data Guard Concepts and Administration Database instances, Data Guard

And last but not least, three have been made obsolete in 12c:

Name Expanded Name Short Description Long Description External Properties
DRnn ASM Disk Resynchronization Slave Process Resynchronizes the contents of an offline disk When a disk online SQL command is issued on a disk or disks that are offline, ASM spawns DRnn. Depending on the load, more than one slave may be spawned. ASM Instance
FDnn Oracle ASM Stale FD Cleanup Slave Process Cleans up Oracle ASM stale FDs on foreground processes This process cleans up Oracle ASM stale FDs on foreground processes if an Oracle ASM disk is globally closed. Database and ASM instances
Vnnn ASM Volume I/O Slave Process Initializes ASM volume contents during creation This process is responsible for initializing the ASM volume during creation. ASM instance

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