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Adding DASD &/or Memory decreases performance ???!!!!
It doesn't seem right that adding such resources will decrease performance. Additional memory and disk will almost always have a positive effect. In those rare instances where a decrease is found, it's usually minor (less than 10%) and due to trading off higher capacity components, but fewer of them. Therefore you have fewer channels/busses in operation and lose some of the advantages of parallel I/O. It can also happen that higher capacity components are individually slower then their lower capacity counterparts. As long as the comparisons are from equivalent hardware generations, the effect is again usually minimal. The one thing is that you have a bottom end, P05 Model 170 "Invader". These units were designed with price being the top priority, not upgradability or performance. The last time we upgraded, our IBM rep let us know that these type of units were intended to be treated more like a personal computer. Therefore the idea was that customers were much more likely to perform entire box swaps when capacity became a problem than doing a lot of upgrades. Therefore IBM put much less effort in making various upgrade options. You might have encountered an effect caused by some sort of extended or lower speed bus. However, you surely can't be surprised that you lost 15% of your ASP. Newer versions of OS/400 are always bigger than older versions. That, plus you upgraded 6 releases in one go! -
Adding DASD &/or Memory decreases performance ???!!!!
I was reading an old AS400 spec sheet from 2000 & it noted the different CPW figures for a 170 (which I have) in constrained & not-constrained. It said the constrained (the much lower CPW ratings, 125 vs. 210 batch) CPW was defined as the processor being "constrained" by the 170 having the "maximum DASD & Memroy configurations". I just upgraded our box to v5r3 (from v4r2) & the whole process chewed up about 15% of the ASP ! I now am looking to add more dASD & was hoping to max out the available disk slots since used disks are so cheap. HOWEVER, do I now need to consider that the more DASD I add, the more my performance is going to suffer ??? TIA MartinComment
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Adding DASD &/or Memory decreases performance ???!!!!
Brian, Thanks for the input. Yeah, I knew about the 15% beforehand as I did this whole upgrade on a 2nd test box before attempting it on the production machine: that made things much less nerver-wracking during the production upgrade. Our 170 is actually a P10, but I see your point about the marketing strategy & upgrade limitaions. The current box has 4 6.5 gig drives & 1 8.5 gig drive, the load source. I was wondering if I should go with 17.5 gig drives or the 8.5 gig ones. You know where I could do/get some objective research on what the pitfalls might be ? Thanks again. MartinComment
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