We were in the midst of a huge performance problem today on a 6 way RAC and this occurred enough times to be both unusual and interesting. Even more interesting is that this wait looks like it's related to I/O some way. Even more interesting, we had identified writes as a real issue, especially redo writes. Thanks for the explanation!! Always good to hear from the folks that wrote the book on waits! Thanks again John ----- Original Message ---- From: K Gopalakrishnan <kaygopal@xxxxxxxxx> To: orclwzrd@xxxxxxxxx Cc: oracle-l <oracle-l@xxxxxxxxxxxxx> Sent: Thursday, October 9, 2008 5:18:12 PM Subject: Re: gcs log flush sync John, I don't discount this as an idle wait. Basically you (LMS) are/is waiting for LGWR to flush the pending redo during CR fabrication. Without going too much in to details, you can turn off the behaviour by setting _cr_server_log_flush to false. Are you looking for the details on this wait event or having a performance problem and suspecting the wait? On Thu, Oct 9, 2008 at 12:22 PM, John D Parker <orclwzrd@xxxxxxxxx> wrote: > Anyone have any solid information on this wait event? The 10.2 docs indicate > it's an idle event, but it's name is far too ominous to just be an idle > event of the same pedigree as null event... > > Thanks, > John > > PS. I'm seeing it on a 6 way 10.2.0.4 RAC on RHEL ES 4 > > -- Best Regards, K Gopalakrishnan Co-Author: Oracle Wait Interface, Oracle Press 2004 http://www.amazon.com/exec/obidos/tg/detail/-/007222729X/ Author: Oracle Database 10g RAC Handbook, Oracle Press 2006 http://www.amazon.com/gp/product/007146509X/