Standard Background Processes

Depending on the options installed and the specific configuration of an Oracle installation, many background processes may be required. There is, however, a core set of background processes required for every Oracle instance, which are found in any machine on which Oracle is running, from Personal Oracle on an Intel-based PC to the largest Unix server. The failure of any one of these processes indicates failure of the entire Oracle instance; when such failures occur, the instance must be restarted.

The standard background processes include:

  • Database Writer (DBWR or DBWn)

  • Log Writer (LGWR)

  • System Monitor (SMON)

  • Process Monitor (PMON)

  • Checkpoint (CKPT)

  • Archiver (ARCH)

  • Shared Server (Snnn)

  • Dispatcher (Dnnn)

  • Recoverer (RECO)

  • Lock (LCKn)

  • Parallel Query (Pnnn)

  • Queue Monitor (QMNn) (Oracle8 only)

  • Job Queue (SNPn)

The following sections briefly describe these processes.

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