Oracle Processes
		There are server and background processes. 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 databasebuffer to the datafiles. How many DBWn Processes are started is determined by the initialization parameter DB_WRITER_PROCESSES. DBWR also writes the actual SCNwith 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 databasereceives 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 ARCHIVELOGis enabled. Dnnn The Dispatcher Process is used in a shared serverenvironment. Snnn The Shared Server Process is used in a shared serverenvironment. 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$session.type = 'BACKGROUND' Showing the processes On Unix, the Oracle Processes can be listed with something like ps -eaf | grep ora Foreground processes While background processes do the work for Oracle itself, foreground processes do the work for clients (such as SQL statements). Foreground processes are created by the listener. Foreground processes have v$session.type = 'USER' Coordinating the processes' work Oracle uses semaphores to coordinate the work for the processes.