Re: Online 7.12 Tunning [more info]

On Tue, 23 Sep 1997, Nigel Gall wrote: } } Hi! } } Just a question on your response: } } At 07:11 PM 9/22/97 EDT, Art Kagel wrote: } > } > [... snip ...] } > } >3) You have but one AIO VP, since the CPU VP does work for other threads } >while waiting for the AIO VP to return many IO requests can queue up. } >Informix recommends 1.5 AIO VPs per chunk for version after 7.20 and } >2.5->3 AIO VPs for earlier ODS versions (the AIO code was rewritten in } >7.20 and is much faster). With the 6 chunks you have you should } >configure 15-18 AIO VPs (yes even on a single CPU machine) lean toward } >15 if adding chunks is a rare thing and 18 if the database is growing. } > } } In Elizabeth Suto's book INFORMIX-OnLine Performance Tuning, on pages } 67-69, she addresses AIO VPs. If one has KAIO enabled, then one would only } require a few AIO VPs to handle non-raw file I/O, such as to online.log or } $ONCONFIG, as well as any cooked chunks. Has this changed in post ODS } 7.20? I've lost the original message from Serafim, but I think he } mentioned that he had KAIO turned on. I do not remember having seen any KAIO threads in the onstat -g glo report, though with only one CPU/CPU VP there would be only one KAIO thread so I might have missed it. I've got Suto's book and one day I must read it, it has not been hubris that has kept me from it just too busy, sounds like she has some insight to contribute. Art S. Kagel, kagel@bloomberg.com