On Fri, Mar 14, 2008 at 10:44 AM, John Hallas <john.hallas@xxxxxxxxxx> wrote: > The main misunderstanding I have is the difference between 95% and 90%. > The 2nd node is available but not in use. I know there will be heartbeat > and other maintenance work going on and I am also aware that the cache > fusion will keep the 2 SGAs in sync, however I have been searching for more > information on what is happening in the preffered/available modes and any > thoughts appreciated. > When you say "preferred/available" are you referring to the "Service" you created? If so then the only effect of this is that all connections are going to the preferred node - however the other node is up and running and fully part of the cluster. One thing that comes to mind right away - even though your second node is "not in use" it still maintains a complete mirror of the GRD (global resource directory - things like cluster-wide locks). Also, there's a good amount of additional messaging related to SCN generation. Just some shots in the dark, but I wonder if you could statically force all lock masters to the preferred node and decrease SCN traffic by tweaking something like the MAX_COMMIT_PROPOGATION_DELAY init param? That might get you some of those percents back... ** PS - I'm loving this whole thread because it's a perfect example of the bogus hype around RAC. Clustering is powerful technology and honestly, a lot of applications will scale well with no modifications on RAC. (The well-designed ones.) But clustering is complicated and if a sales person gives the impression that you can just run any application on RAC to make it magically faster -- baloney!!!! -- Jeremy Schneider Chicago, IL http://www.ardentperf.com/category/technical