My two cents: I agree with Shane. The rule of thumb used to be not to go over 2:1 logical to physical on a CEC, when adding up all of the logicals for all the lpars, but I don't know what's recommended now either.
At the 2:1 ratio, we saw the performance elbow on 9672 and 2064 systems. 2084 and 2094 seem to have done something (cp speed? Better pr/sm logic?) that makes it more like 2.5:1 at crunch time. We've run 2094 systems routinely at 3.5:1, which is fine up until the CEC is around 85% physical busy (1.2% lpar management time). After that, it's got to come down to something closer to 2.5:1 (0.6% lpar management time) or engines start getting real short. IRD's cpu vary seems to do a good job at staying on top of this until the CEC gets past 99.7% physical busy. And it's still true that you can get "best" utilization from a CEC that's 100% busy with lpars pushing for more, by "squaring" the box so the weights and logical cp assignments match up to almost simulate a "dedicated CP" configuration. Of course, if you have lpars that are sized for anything smaller than one engine, you wouldn't be able to get away with this anymore. I'm sure some of you have had the same experiences, when the legitimate workload overruns the capacity of the box and there's no money allocation for upgrades coming any time soon, and you have to go back to simulating basic or dedicated cp mode. Best regards, Gary Diehl -----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of Shane Subject: Re: LPAR performance questions ? Pick a (low) number. For me 2.5:1 would be where things start to get rubbery. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
