Re: Informix Performance Issues

"Art S. Kagel" <kagel@bloomberg.net> wrote in message ... <snip> > Time since reset: 202.33 > ixda-RA: 38469248 > idx-RA: 109333718 > da-RA: 748405431 > RA-pgsused: 894562606 > > BR = (96935964 / (96935964 + 2242129221)) * 100.00 = 4.1400 > BTR = (((96935964 + 2242129221) / 300000) / 202.33) = 38.5354/hour > RAU = (894562606/(38469248+109333718+748405431)) * 100.00 = 99.8100 > <snip> > Your ReadAhead Utilization rate is 99.81% which is just fine! DO NOT MUCK > WITH THE RA values much. You may try 32 & 4 instead of 8 & 4 but DO NOT go > hog wild as TBP suggests. I think that will be disasterous for throughput. > Humm, well, proof would be in the pudding, but I think that is a "rash" statement to make without knowing more details about what the geezer is using this instance for. 99.8100 is a good number, but doesn't that infer that there is scope for improved usage if there is more read ahead? I think I stated to "do something stupid once in your life" (I have acheived that regularly) and set : RA_PAGES 1024 RA_THRESHOLD 64 which is pretty stupid UNLESS, I am the only person on this system and I want to fly through a huge table, and then it is pretty good. Looking at a compromise (and we do not know what this geezer has), let's say he has 8 big report type users, and 32 little OLTP type users, then : RA_PAGES 128 RA_THRESHOLD 32 would be okey dokey. BUT ... proof is in the pudding, not in the decimal places :) So, what did the geezer do?