The Average Time to Sync a Redo Log Entry alarm is activated when the time taken to write redo log entries during a commit exceeds a threshold. Oracle sessions that perform a COMMIT must wait for redo log writes to complete before they can continue processing; redo log devices should therefore be placed on fast devices.
Most modern disks should be able to process a redo log write in less than 20 milliseconds, and often much less. To reduce redo write time see Improve Redo Log Writer Performance.
Note: In earlier versions of Spotlight on Oracle, this alarm was known as the Average Redo Write Time alarm.