Re: Checkpoint duration increase with 7.22.UC1

In article <5lak28$ssn@cssun.mathcs.emory.edu>, Kernoal Stephens <kernoals@earthlink.net> arranged the electrons to spell out: > With 7.13.UC2 my checkpoint duration was averaging 4.5 seconds. > I used the same onconfig settings with 7.22.UC1 and my average > checkpoint duration > is 8.4 seconds. > What has changed to cause the checkpoint duration to increase? > ONCONFIG FILE > ##################### > > BUFFERS 172032 This may have something to do with it. When we went to 7, we noticed a similar problem. Under 5, having buffers set as high as we had memory never gave us any grief, but there's a much more measurable correlation between cache size and checkpoint duration under 7. We cranked buffers down until a performance loss was found (to a much lower setting than we expected) and then up a little. This got us significantly shorter checkpoints. I don't know if this is your situation or not, but it may be worth a try. As an aside, we got an EMC disk subsystem in to play with, and were able to drag buffers down to, oh, 1000 or so. The danged thing got faster every time we lowered buffers (and allowed the subsystem to cache, with all of the attendant network overheads). This leads me to believe that Informix doesn't cache as well as it could, but that was (in all fairness) only one test. DOH! I just reread your message and noticed that you were talking about 7.13 -> 7.22. My apologies. Still, this may be useful to other people doing 5 -> 7, or may help you lower checkpoint duration (although it isn't the original problem) so I'll send it anyway. -Richard