Re: Extended checkpoint times

I had a problem in November of checkpoints blowing out to 10 minutes or so = during the evening like your manifestation. I was advised from tech support that checkpoints can blow out two ways. 1. When checkpoint is requested, Online freezes all sessions for users not = in a critical section and waits for remainder to exit critical section = before freezing their sessions. A critical section is most likely to be a physical write to disk. 2. If Online is carrying out some large unusual process, like a large = table load, this can also cause checkpoints to blow out.=20 It is possible that a disk problem could be the cause. To investigate = this possibility, during an interval when system is frozen do the = following; 1. ID the sessions in critical sections. 2. onstat -g sessid to ID the tables being connected to. 3, ID the dbspace of the tables concerned. 4. ID the raw partition that this relates to. In our case the sysadmin had been messing around with disks getting the = machine ready for a solaris upgrade. I don't know why this might have = affected online but the problem did go away after the disk got sorted out. = =20 HTH Peter Tashkoff <tashkop@iname.com> Zespri International Limited Std Disclaimers Apply All rights reserved. No party may use this document to vilify another. Zespri New Zealand Kiwifruit, The World's Finest >>> anonymous masquerading as Mark said >>> Hi, We are trying to investigate a series of overly long checkpoints on one of our informix databases, here is a snippet of the online.log file detailing the events: 21:16:55 Checkpoint Completed: duration was 76 seconds. 21:22:04 Checkpoint Completed: duration was 6 seconds. 21:27:16 Checkpoint Completed: duration was 8 seconds. 21:40:15 Checkpoint Completed: duration was 476 seconds. 21:45:29 Checkpoint Completed: duration was 10 seconds. 21:50:36 Checkpoint Completed: duration was 2 seconds. 21:55:42 Checkpoint Completed: duration was 3 seconds. 22:03:22 Checkpoint Completed: duration was 155 seconds. In general we have checkpoint times around the 6-7 second region, but recently we've seen several occurances were informix goes catatonic on us whilst doing a 400 second checkpoint! Are there commands available to analyze the log files to see which sql statements were running upto when the checkpoint took place - or if you know of anything that could cause these kinds of checkpoint times that would be useful. From the informix manual it states checkpoints wait for critical code sections to complete before it can complete so in theory if an application hung for whatever reason inside a critical code section it could hold up a checkpoint - forever? or until informix decided the application was not responding? Thanks in advance, Mark