log buffers & checkpoints

Are the io rates of log buffer below normal or is it too high? Informix Dynamic Server Version 7.31.FC7 -- On-Line -- Up 2 days 22:48:58 -- 1479648 Kbytes Physical Logging Buffer bufused bufsize numpages numwrits pages/io P-1 127 128 1340153 10906 122.88 phybegin physize phypos phyused %used 200035 245000 164777 1407 0.57 Logical Logging Buffer bufused bufsize numrecs numpages numwrits recs/pages pages/io L-2 46 128 20358687 997847 12847 20.4 77.7 Subsystem numrecs Log Space used OLDRSAM 20358687 2005637000 Should the logical and phyisical log buffers be same?Does the size of the the log buffers affect the checkpoint durations?Thanks... Sent via Deja.com http://www.deja.com/

the book says to try to keep the ratio of pages/io divided by bufsize to be about 75%. With that said, your physical log buffer a little too small and your logical log buffer is a little big. No, the physical log buffer and logical log buffer do not have to be the same size. But if your performance tuning, I'd print the output from onstat -p to see what your read/write cache ratios are. Those are the numbers to focus on. 85% for writes, 95% for reads is what you should aim for. Checkpoint durations are caused by a multitude of things, log buffers being one of them. But if you really want to affect checkpoint durations, mess with the LRUMAX/MIN setting in your onconfig. Those will determine how often buffer pages get flushed thereby affecting checkpoint durations. Murat YILDIZ wrote: > Are the io rates of log buffer below normal or is it too high? > > Informix Dynamic Server Version 7.31.FC7 -- On-Line -- Up 2 days > 22:48:58 -- 1479648 Kbytes > > Physical Logging > Buffer bufused bufsize numpages numwrits pages/io > P-1 127 128 1340153 10906 122.88 > phybegin physize phypos phyused %used > 200035 245000 164777 1407 0.57 > > Logical Logging > Buffer bufused bufsize numrecs numpages numwrits recs/pages pages/io > L-2 46 128 20358687 997847 12847 20.4 77.7 > Subsystem numrecs Log Space used > OLDRSAM 20358687 2005637000 > > Should the logical and phyisical log buffers be same?Does the size of > the the log buffers affect the checkpoint durations?Thanks... > > Sent via Deja.com > http://www.deja.com/ -- Phillip Tien Database Administrator Whole Foods Market, Inc. Children need encouragement. If a kid gets an answer right, tell him it was a lucky guess. That way he develops a good, lucky feeling.