Log File Sync Event
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Description
When a user session commits (or rolls back), the sessions redo information needs to be flushed to the redo logfile. The user session will post the LGWR to write the log buffer to the redo log file. When the LGWR has finished that it will post the user session.
User Action
A drilldown is available to the Redo Analysis Chart for further analysis of the LGWR process. This event means that the LGWR process needs to be sped up.This is related to the throughput of the disk. Do NOT put redo on raid 5. Raid 5 is not efficient for writes. Use multiplexed redo on different spindles or mirrored disks for redo.
Good Notes on all events;
http://www.dbspecialists.com/presentations/wait_events.html