This is a continuation of a previous thread about =91log file sync=92 and =91log file parallel write=92 events. Version : 9.2.0.8 Platform : Solaris Application : Oracle Apps The number of commits per second ranges between 10 and 30. When querying statspack performance data the calculated average wait time on the event =91log file sync=92 is on average 10 times the wait time for the =91log file parallel write=92 event. Below just 2 samples where the ratio is even about 20. "snap_time" " log file parallel write avg" "log file sync avg" "ratio 11/05/2008 10:38:26 8,142 156,343 19.20 11/05/2008 10:08:23 8,434 201,915 23.94 So the wait time for a =91log file sync=92 is 10 times the wait time for a =91log file parallel write=92. First I thought that I was hitting bug 2669566. But then Jonathan Lewis is blog pointed me to Tanel Poder=92s snapper tool. And I think that it proves that I am NOT hitting this bug. Below is a sample of the output for the log writer. -- End of snap 3 HEAD,SID, SNAPSHOT START ,SECONDS,TYPE,STATISTIC , DELTA, DELTA/SEC, HDELTA, HDELTA/SEC DATA, 4, 20081105 10:35:41, 30, STAT, messages sent , 1712, 57, 1.71k, 57.07 DATA, 4, 20081105 10:35:41, 30, STAT, messages received , 866, 29, 866, 28.87 DATA, 4, 20081105 10:35:41, 30, STAT, background timeouts , 10, 0, 10, .33 DATA, 4, 20081105 10:35:41, 30, STAT, redo wastage , 212820, 7094, 212.82k, 7.09k DATA, 4, 20081105 10:35:41, 30, STAT, redo writer latching time , 2, 0, 2, .07 DATA, 4, 20081105 10:35:41, 30, STAT, redo writes , 867, 29, 867, 28.9 DATA, 4, 20081105 10:35:41, 30, STAT, redo blocks written , 33805, 1127, 33.81k, 1.13k DATA, 4, 20081105 10:35:41, 30, STAT, redo write time , 652, 22, 652, 21.73 DATA, 4, 20081105 10:35:41, 30, WAIT, rdbms ipc message , 23431084, 781036, 23.43s, 781.04ms DATA, 4, 20081105 10:35:41, 30, WAIT, log file parallel write , 6312957, 210432, 6.31s, 210.43ms DATA, 4, 20081105 10:35:41, 30, WAIT, LGWR wait for redo copy , 18749, 625, 18.75ms, 624.97us When adding the DELTA/SEC (which is in micro seconds) for the wait events it always roughly adds up to a million micro seconds. In the example above 781036 + 210432 =3D 991468 micro seconds. This is the case for all the snaps taken by snapper. So I think that the wait time for the =91log file parallel write time=92 must be more or less correct. So I still have the question =93Why is the =91log file sync=92 about 10 times the time of the =91log file parallel write=92?=94 Any clues?