Re: Too-frequent checkpoints; which parameters to check?

In article <331FF103.7F5C@lava.net>, Bob Cunningham <bob@lava.net> writes >I've got a situation with On-Line 7.22 (SPARC, Solaris 2.5.1) where >we get flurries of checkpoints at short intervals, during >some update periods that look like: > >23:35:07 Checkpoint Completed: duration was 2 seconds. >23:35:14 Checkpoint Completed: duration was 1 seconds. >23:35:22 Checkpoint Completed: duration was 1 seconds. >23:35:30 Checkpoint Completed: duration was 1 seconds. >23:35:38 Checkpoint Completed: duration was 1 seconds. >23:35:46 Checkpoint Completed: duration was 2 seconds. >23:35:53 Checkpoint Completed: duration was 1 seconds. >... >23:45:06 Checkpoint Completed: duration was 1 seconds. >23:45:14 Checkpoint Completed: duration was 1 seconds.> >Needless to say, queries slow to a crawl when there's >a checkpoint every few seconds. > >Log files aren't a problem, but I'm not sure exactly what is... > >Which tuning parameters should I be looking to change: >PHYSFILE, the LRU* ones, or ??? Informix Online Dynamic Server Administrator's Guide, Volume 1 Version 7.1 Page 12-52/3 : events that initiate a checkpoint. - The checkpoint interval, specified by the configuration parameter CKPTINTVL, has elapsed and one or more modifications have occured since the last checkpoint. ***CHECK CKPTNTVL*** - The phyiscal log on disk becomes 75 percent full. ***CHECK PHYSFILE*** - Online detects that the next logical log file to become current contains the most recent checkpoint record. ***USE tbstat -l TO MONITOR LOGICAL LOG USAGE*** - The OnLine Administrator initiates a checkpoint from the OnMonitor, Force-Ckpt menu of from the command line using onmode -c. ***CHECK CRON/AT JOBS FOR onmode COMMANDS*** - Certain Administrative tasks such as adding a chunk or a dbspace, take place. ***UNLIKELY - MONITOR NUMBER OF CHUNKS WITH onstat -c *** -- David Williams