Re: Informix 5 Performance Issues

Remember - YMMV, etc: On 16 Apr 97 at 17:04, Phantom173 wrote: > We have been told by a consultant that a move to Informix 7 would > benefit us because (a) Informix 7 would reduce the number of connects > (and therefore processes) associated with the elephants, and (b) it > would allow multi-threading in the database. Our DBA agrees that this > might provide some benefit, but doubts very strongly that this would be > significant given the facts stated above. He is arguing for an increase > in the number of processors (plus some dramatic redesign of the database > and the application). Honestly, I know it's a cop-out, but you really should try it to see whether it works. I agree with your consultant. I couldn't see how many processes you were running in total, but context switching can become a significant overhead. I'm also sure that Sequent supports processor affinity - this means that you could tie up a CPU just to run an Online 7 virtual process, with resultant performance benefits. A redesign of your application may be important for other reasons, but I would hesitate to use that as my first step to improve performance!! > In fact, the DBA is arguing that we remove the 16-586 processors and > replace them with 32-486 processors (50MHz). His logic is that, while > each individual process will run 17% slower, in total things will run > faster because the extra processors means we won't have processes > waiting for 6-15 minutes before they get to run. We have maxed out the > Sequent machine on 586 processors, so we can't add more of those. In fact, you would probably get the best performance if you added more CPUs *and* switched to 7. 7's internal parallelism really takes advantage of multiple resources far better than 5.x. > The questions I have are: > > 1. Forgetting all the other benefits of Informix 7, will we get any > significant benefit from v7 due to reducing the number of connects and > multithreading. I believe so, yes. > 2. Is the DBA's logic sound? Will we get an overall improvement from > having more processors even though they are individually slower. Yes. > 3. If the DBA is correct, will going to 32 processors overwhelm > Informix 5? Can it handle all the requests that will come from these > processors, or will it become the bottleneck. The largest benchmark I have ever seen for Informix involved 26 CPUs - I don't know if they felt that's as far as it would scale or what. I would upgrade to 7 in either event. > 4. If we go with the 32 processors and Informix becomes a bottleneck, > will v7 help because of its multi-threading. Yes. > Sorry for the long-winded explanation and multi-part question, but I'm > really getting desperate and the CFO is on my back for answers. Good luck. -- Ciao, Billy Nose to the ground and ear to the grindstone in: Johannesburg Why is it hard for women to find men who are sensitive, caring and good looking? Because those men already have boyfriends.