Re: System tuning

The person who replied to your article is right on the money. You CAN NOT increase the buffer variable and expect the I/O performance go up. If the system is running out of memory becuase your database is now taking more memory space it will cause paging and process swapping and cause the performance to go down. As far as all the time going to CPU VP's please check the following: 1) Are you running exactly the same application as before ? 2) use "vmstat 5 500" command to make sure that your application is not causing an infinte loop in the CPU vp's. For understanding what is some of the parctical uses of onstat utility outputs please chack out the following book: Informix Online performance tuning By Elizabeth Suto Prentice hall/Informix press ISBN 0-13-124322-5 Regards, <<<saeed>>> In <4j4u93$fks@atglab10.atglab.bls.com> tolly.brumbelow@bridge.bst.bls.com (tolly brumbelow) writes: > >informix@asl3.asl-labs.bc.ca (Informix Sysadmin) wrote: > > >>Hi...running the online engine v7.1 > >>We have been having performance nightmares, so we have been attempting to >>modify some parameters, however we appear to be unable to decipher many >>of the outputs from the onstat command. Most recently, we increased our >>BUFFERS value, and the output from onstat -g glo changed from having all >>the time go to AIO vp's to CPU vp's. Can anyone decipher this occurance? >>Does that mean that we WERE blocked on AIO, but now are blocked on CPU? >>Why can't there be a comprehensive explanation of ALL the output of >>onstat ?????? What's the use of all these stats tools when they don't >>explain what is good, what is NOT good :( > >>B. > >> ----------------------------------------------------------------------- - >> |Brian P. Hampson Internet : brian@asl-labs.bc.ca | >> |System Administrator, Air(2m/70cm): VE7NNW | >> |Analytical Service Labs Fidonet : Brian Hampson 1:153/733| >> |Vancouver, BC | >> |+604-253-4188 | >> | Specialists in Environmental Chemistry | >> | | >> ------------------http://www.asl-labs.bc.ca/--------------------------- - > > >I would get the unix admin. to check for paging and swapping. You may >have moved the io out of informix and put it on the os. >Informix 7.1 does take more system overhead than 5.x and with the >small amount of memory you have you may have overloaded the os when >you increased the buffers. >Raid 5 cost you on performance if you have a high updated system > >-- >Tolly Brumbelow, Informix DBA >email:tolly.brumbelow@bridge.bellsouth.com >