control file parallel write等待事件

This event occurs when a server process is updating all copies of the controlfile.

Controlfile updates occur in the following situations:

A checkpoint is reached

The session starts a control file transaction (to make sure that the control files are up to date in case the session crashes before committing the control file transaction)

The session commits a transaction to a control file

Changing a generic entry in the control file, the new value is being written to all control files


If this wait is significant, check for I/O problems. Possible points of trouble include controllers and physical disks. Check for all of the controlfile copies.

Limit controlfile copies, but consider the increased risk of losing all controlfiles at once.

If possible, use Asynchronous I/O.

Move the controlfiles to drives with less I/O activity.

Frequency of controlfile access is governed by activities such as Redo Logfile switching and Checkpointing. Therefore focus on tuning these activities if the I/O paths are healthy.






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