Re: Informix tuning

Neil_Truby@iiug.org wrote: > > In article <35EBF8D1.50387093@acer.de>, Kai says... > > > >Hi, > >we have a 4 CPU, 1GB, SCO 5.0.4 machine running Informix ODS 7.20.UC3. > >onstat -p shows only 74% bufwrites and 94% bufreads. The machine is> >running OLTP only and uses Mylex Raid controller. How do I optimize for > >the Mylex? Do the recommendations still hold (number of physical > >disks=CLEANERS etc..)? > > > >We have following settings in $ONCONFIG: > >NUMAIOVPS 4> Does SCO support KAIO? In which case, activate it and reduce this to 1. > > >CKPTINTVL 60> This is very low. The default is 300 I think, although I usually use 900. > There's nothing inherently wrong in forcing a checkpoint every minute if you > need to for, say, recoverability reasons, but it does mean that the amount of > time in which a modified page is available for re-use before being written to > disk and forced out of the cache is short. This will inevitably lower the write > cacheing rates you can achieve. I'm not sure I like the term 'forced out of the cache'. The page stays in the buffer cache of course, being moved from the modified side to the free side. It just means any changes to the same page will require another write to disk. Cheers, -- Mark. +----------------------------------------------------------+-----------+ |Mark D. Stock - Informix SA http://www.informix.com |//////// /| |mailto:mdstock@informix.com http://www.informix.com/idn |///// / //| |http://www.iiug.org +-----------------------------------+//// / ///| | Tel: +27 11 807 0313 |If it's slow, the users complain. |/// / ////| | Fax: +27 11 807 2594 |If it's fast, the users keep quiet.|// / /////| |Cell: +27 83 250 2325 |Therefore, "No news: travels fast"!|/ ////////| +----------------------+-----------------------------------+-----------+