onmode -B

greetings! apparently, onmode -B is an undocumented feature that many people use. We are running informix 9.21 HC5-1 on UNIX-HP ver 11.00 and have employed the contorted method of running a cron job that fires onmode -B, sleeps for 2, then runs onmode -c. It has taken our long & painful checkpoints that use to last anywhere from 20-132 seconds (!) and dropped checkpoints to 1 second - a remarkable improvement. What I would like to know is if anyone know if there is a price to pay for doing this? We currently have a case in Informix support and have not heard anything back yet so we are going with this "solution" for now because it is really needed. TIA, Tom

"tomL" <schmotom@yahoo.com> wrote in message news:e70357eb.0306131324.46d4e8b8@posting.google.com... > greetings! > apparently, onmode -B is an undocumented feature that many people use. > > We are running informix 9.21 HC5-1 on UNIX-HP ver 11.00 and have > employed the contorted method of running a cron job that fires onmode > -B, sleeps for 2, then runs onmode -c. It has taken our long & painful > checkpoints that use to last anywhere from 20-132 seconds (!) and > dropped checkpoints to 1 second - a remarkable improvement. What I > would like to know is if anyone know if there is a price to pay for > doing this? > > We currently have a case in Informix support and have not heard > anything back yet so we are going with this "solution" for now because > it is really needed. I think your approach is incorrect. By clearing buffer every 2 min, u are losing the benefit of buffer read. What you should do is to automatically do onmode -B some 15-20 seconds before checkpoint. However the question is, how do we know when was the last checkpoint. Except for online log file, Informix does not record anywhere when the checkpoint occured. So u may have to write a perl program to parse the onling log file and note the last checkpoint time and add CKPTINTVL to it to know accurately when is the next scheduled checkpoint. Just 15-20 seconds before the next scheduled checkpoint, it should fire onmode -B. Pls note that this will fail when there is a forced checkpoint due to 75% of physical log full or any other special event.