log file sync includes the time it takes to post the LGWR process as well as
the time it takes to flush the buffer down to the datafile.
log file parallel write is only the time it takes to write out the log
information to disk.
So in short, log file parallel waits shows delay in IO to actually process
the write. Where as significantly higher log file sync wait time over the
log file parallel waits shows contention on the LGWR and it's latches.
Steve, please correct me if I am wrong with this assesment.
This is something my research has always lended me to believe.
"Walking on water and developing software from a specification are easy if
both are frozen."
Christopher R. Spence
Oracle DBA
Fuelspot
-----Original Message-----
Sent: Thursday, June 14, 2001 9:46 PM
To: Multiple recipients of list ORACLE-L
Looking at some old Q&A on Steve's site (www.ixora.com.au) and found a post
containing this...
"The ratio of your log file sync to log file parallel write waits indicates
that your log_buffer is much too big. Drop it back to 160K. "
What exactly is the ratio suppose to be and how do these two wait events
differ exactly.
Thanks,
Ethan Post
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