Re: Optimizing Informix IO

Hope the following suggestion will be useful Question1--> If we print IO statistic by VP we can identify the number of KAIO vp's running. Command: onstat -g iov We can initialize the KAIO by setting environmental variable KAIOON=1. At 06:10 PM 4/7/98 GMT, you wrote: >In article <6gde5t$g4t$1@news.xmission.com>, > "Narkinsky, Pat" <Pat.Narkinsky@rivhs.com> wrote: > >> >>System Manifest: >>INFORMIX-OnLine Version 7.14.UD1 >>AIX 4.3.0.0 >>IBM RS/6000 S70, 12 Processors, 8GB of memory >>IBM SSA Disk Array >> >>We are running an Informix Based financial application with >>approximately 150 simultaneous users, and have experienced persistent >>performance problems. Currently, we have thrown a ridiculous (IMHO) >>amount of processor at the problem and are getting adequate performance. >>However, we will soon be adding users, and I am concerned at the fact >>that we: >>1) Have no upgrade path for hardware; we are at the top of the line >>now. >>2) Are still experiencing 0% Idle Time (according to sar). >>3) Have to add approximately 100 users in the next six months. >>Our problems are clearly IO related: examination of the output of sar >>indicate we are spending approximately 80% of our time waiting for IO. >> >>First question: we are running with NUMAIOVPS equal to 1. Could this be >>aggravating our IO problems? How can I tell if we are running KAIO? >> >>Second question: I've heard mention on this list to the effect "Informix >>doesn't like RAID". Could someone clue me in on the considerations >>here? >> >>Third: I've got 8GB of memory, however I am only using approximately >>1.5GB. Would it be possible/advisable to try to get the engine to use >>more of that memory? Will this make my checkpoints last too long? >> >>Fourth: One of the busiest dbspaces on the system is "tempdb1" >>(according to 'onperf'). I have the following line in my onconfig file: >> DBSPACETEMP tempdb1:tempdb1:tempdb2 >>What is the significance of the double listing for tempdb1? Is this >>probably intentional, or is it the result of a typo on the part of my >>vendor? Would this account for the fact that tempdb1 is MUCH busier >>than tempdb2? Should I change it? >> >>Thanks! >> >>Patrick > >Question the First -> under HP/UX when I bounce the engine with KAIO >enabled, I get this written to the online log: > >DR: DRAUTO is 0 (Off) >HPUX Version B.11.0 -> Using select based KAIO >INFORMIX-OnLine Initialized -- Shared Memory Initialized > >Question the Second -> (again HP) we tried using an HP model 20 array >with RAID 5. Performance was sooooo slooooow we yelled at HP so loudly >they took back the array and credited full amount towards purchase of >a bunch of small disks. Informix much happier with 40 2Gig disks than >it was with one 80 Gig array. > >Question the Third -> I've never been able to figure out how adding more >memory speeds things up, as long as you're not swapping and have plenty >of buffers. I see no difference on our box between 1 Gig RAM and 2 Gig RAM. > >Question the Fourth -> Cool! Never thought of specifying the same temp >space twice on the DBSPACETEMP line. Am guessing Informix treats this as >it would three temp spaces, simply uses the same dbspace for the first >two temps. May be way to maximize leverage when have some fast and some >slow disks - specify each fast disk twice, each slow disk once. Have to >try this... > >Hope some of this is useful... > >Ray Garrison > > -###################################################################-####### -Selvakumar Rajagopal -Database Specialist Endura Software Corporation -Technical Service Group Seattle, WA - Phone:(206) 522-0055 - Fax:(206) 522-0053 - E-mail: -selvakumar.rajagopal@enduracorp.com - Web: http://www.enduracorp.com -###################################################################-#######