tuning questions

I recently doubled the size of my database, and have been tuning for a few days now. IIUG CDI Glimpse has been a tremendous help, especially the posts of Art Kagel, David Williams, et al. My thanks to them. My environment: HP 9000 J200 , 2 processors, 256 megs, HP-UX 10.01, database dedicated Informix ODS 7.22.UC1 Database around 16 gigs, 10 of which is used 6 Dbspaces, all mirrored, 4 cooked 2 raw KAIO just enabled Basically 1/2 DSS and 1/2 OLTP MULTIPROCESSOR 1 NUMCPUVPS 1 SINGLE_CPU_VP 1 LOCKS 100000 BUFFERS 15000 NUMAIOVPS 8 PHYSBUFF 96 LOGBUFF 48 CLEANERS 16 CKPTINTVL 300 LRUS 16 LRU_MAX_DIRTY 10 LRU_MIN_DIRTY 5 RA_PAGES 24 RA_THRESHOLD 12PDQPRIORITY 50 A few questions: I cannot seem to get my onstat -F LRU write / Chunk Write ratio any higher than 1:1 or 1.5:1. During the day my checkpoints average only 3-4 seconds: 08:04:01 Checkpoint Completed: duration was 4 seconds. 08:09:04 Checkpoint Completed: duration was 1 seconds. 08:14:09 Checkpoint Completed: duration was 1 seconds. 08:19:16 Checkpoint Completed: duration was 3 seconds. 08:34:32 Checkpoint Completed: duration was 1 seconds. but at night when a lot of batch processing is occurring (beginning at 3:30 AM for instance) they go up to 30-40 seconds, or even higher: 03:15:39 Checkpoint Completed: duration was 1 seconds. 03:31:10 Checkpoint Completed: duration was 19 seconds. 03:36:44 Checkpoint Completed: duration was 30 seconds. 03:42:34 Checkpoint Completed: duration was 47 seconds. 03:47:33 Logical Log 5154 Complete. 03:47:35 Process exited with return code 133: /bin/sh /bin/sh -c /opt/informix/etc/log_full.sh 2 23 "Logical Log 5154 Complete." "Logical Log 5154 Complete." 03:47:36 Logical Log 5154 - Backup Started 03:48:10 Checkpoint Completed: duration was 33 seconds. 03:48:10 Logical Log 5154 - Backup Completed 03:53:47 Checkpoint Completed: duration was 34 seconds. (As an aside, why would a checkpoint not occur for 16 minutes between 3:15 and 3:31 when my CKPTINTVL is 300???) There are no FG writes. I have decreased LRU_MAX_DIRTY and LRU_MIN_DIRTY and increased LRUS and CLEANERS, but no help. My Bufwaits are around 3% of Bufreads and Bufwrites. My read and write cache% are 99% and 97%. How can I get my LRU write/Chunk write ratio to increase (and therefore my checkpoint duration to drop)?? ---------------------------------------------------------------------------------------------------------- My onstat -l physical logging pages/io is always higher than 40 while my physical log bufsize is 48 - this seems great. However........ my onstat -l logical logging pages/io is always lower than 5 while my logical log bufsize is 24. The logical logging pages/io is way too low. How can I increase this? ----------------------------------------------------------------------------------------------------------- My ontape -s lev 0 archives are taking a *LONG* time, like 5 or 6 hours. What could be causing this? Should I make other changes as a result of enabling KAIO? Should NUMAIOVPS go down to 1, even w/ cooked dbspaces?? Would another CPU vp be a good idea? (2 physcial processors) Any insight greatly appreciated. Allen Jantzen, DBA Ned Davis Research