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Posts Tagged ‘oracle background process’

Oracle – LGWR


Oracle LGWR *(Logwriter) is a background process that writes the redo log buffer to the online redo log files. It is started automatically when the database instance is started. If the online redo log files are mirrored, LGWR will write to all the group members simultaneously.

LGWR writes to the redo log files in the following circumstances:

  • A user commits a transaction
  • An online redo log switch occurs
  • Three seconds have passed since LGWR last wrote
  • The redo log buffer is one third full or contains 1MB of buffered data
  • DWBn must write modified buffers to the disk

Further Reading:

http://download.oracle.com/docs/cd/E14072_01/server.112/e10713/process.htm#BABJEHBC

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Oracle – MMON


MMON (Memory Monitor) is an Oracle background process that gathers memory statistics (snapshots) and stores this information in the AWR.

MMON is also responsible for issuing alerts for metrics that exceed their thresholds.

MMON is available from Oracle 10g.

The default for recording an AWR snapshot is hourly.