Instance Processes Flashcards
LGWR
Required
Writes transaction recovery information from the SGA redo log buffer to online redo log files.
PMON
Process Monitor.
Required
Cleans up failed connections and processes. Resets status of active transaction table and removes process ID from list of active processes. Reclaims memory and undoes locks from failed user session.
Wakes up periodically to check whether it is needed, but can be called explicitly. Also restarts some background processes if they are stopped.
SMON
System Monitor
Required
Performs instance recovery after crash using online redo log files, cleans temp segments from dictionary-managed tablespaces and coalesces free space in the DB and manages space used for sorting.
If any dead transactions were skipped during instance recovery because of file IO errors, SMON recovers them once files are back online.
Wakes up regularly to check whether needed. Can be called explicitly.
LREG
Listener Registration
Required
Registers information about the instance and dispatcher processes with the listener
RECO
Recoverer
Required
Feature: Distributed Database
Recovers failed transactions that are distributed across multiple databases when using distributed database feature.
CKPT
Checkpoint
Required
Updates data file headers and control file after checkpoint when change is committed to db.
If incremental checkpoint, just updates ctl file.
MMON
Memory Monitor
Required
Feature: Automatic Workload Repository
Gathers and analyzes statistics used by Automatic Workload Repository feature.
MMNL
Memory Monitor Light
Required
Feature: Active Session History
Gathers and analyzes statistics used by Active Session History feature.
VKTM
Virtual Keeper of Time
Required
Provides wall-clock time (updated every second) and reference-time counter.
DIAG
Diagnosability
Required
Performs diagnostic dumps
DIA0
Diagnosability
Required
Diag process responsible for hang detection and deadlock resolution.
ARCn
Archiver n
Copies transaction recovery info from the redo log files to the archive location. There can be up to 30 of these archival processes.
RVWR
Recovery Writer
Feature: Flashback
Writes Flashback data to flashback logs in the FRA.
ASMB
ASM Disk
Feature: ASM
ASM service
RBAL
ASM Balance
Feature: ASM
Coordinates rebalance activity of disks in an ASM disk group.
CJQn
Job Queue Monitor
Feature: Job Scheduling
Assigns jobs to the job queue process (Jnnn) when using Oracle’s job sched feature.
Jnnn
Job Queue n
Feature: Job Scheduling
Executes jobs that have been scheduled with job scheduling feature.
QMNn
Queue Monitor
Feature: Advanced Queueing
Monitors messages in msg queue when using Advanced Queueing feature.
EMNC
Event Monitor
Event management coordination and notification.
FBDA
Flashback Data Archive
Feature: Flashback
Archives historical records from table when using Flashback feature
Qnnn
Parallel Query Slave
Feature: Parallel Query
Carries out portions of a larger overall query when using Parallel Query feature.
Dnnn
Dispatcher
Feature: Shared Server
Assigns db requests to a queue where they are serviced by shared server processes (Snnn) when using Shared Server feature.
Snnn
Shared Server
Feature: Shared Server
Process shared among several users when using Shared Server feature.
MMAN
Memory Manager
Feature: Automatic Shared Memory
Manages sizes of each SGA component when using Automatic Shared Memory.
RVWR
Recovery Writer
Feature: Flashback
Writes recovery info to disk when using Flashback.
SMCO
Space Management Coordinator
Coordinates various space management tasks. Worker processes identified as “Wnnn”.
DBWn
DBWn Database Writer Required Writes dirty buffers to data files. Up to 100 processes for busy systems. DBW0-9, a-z, BW36-99.
