Fair enough. My reply was in response to the comment (which I apparently forgot to quote) about having 3x real memory for paging space.
Depending on where the problem is, even if you're not paging, more memory could be beneficial if the system was configured to use it appropriately. I.E. if the problem is related to doing excessive I/O and you could eliminate that with additional memory for buffering/caching, then maybe adding memory might make sense. But you do need to figure out why people are complaining before you can come up with a plan for making it better. I'd start with trying to compare a "good" time to a "bad" time to see what is different. Is the difference in paging rates? I/O rates? CPU consumption? CPU Delay? Looking at those at a high level should be relatively straight-forward. Digging into the "why" of the particular metric changed gets more interesting. If your performance reporting tool makes that onerous, remember that we (Enterprise Performance Strategies) do offer free cursory performance reviews and our performance reporting service does have a free tier as well. Contact me off-list if you're interested. Scott Chapman On Sun, 3 Nov 2019 06:16:42 -0800, Charles Mills <charl...@mcn.org> wrote: >"Large memory" is not the situation I am dealing with. It is a modern system >but it is at a service bureau and there is a substantial charge associated >with real memory. My management does not want to just throw money at the >system; he wants some way of seeing whether real memory constraint is a >problem and whether additional real memory improves the problem. "Performance" >is hard to measure because the workload is extremely varied and not directly >under our control, so mostly what we have is subjective: "it's really slow >today." > >Charles > > >-----Original Message----- >From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On >Behalf Of Scott Chapman >Sent: Sunday, November 3, 2019 5:08 AM >To: IBM-MAIN@LISTSERV.UA.EDU >Subject: Re: How display level of paging? > >I'm not so sure that's practical and necessary for the large memory systems >that we have today. > >Last time I looked across a number of customers it was fairly common for LPARs >with hundreds of GB of memory to have paging space < 1x memory. Sometimes much >less. Those with Storage Class Memory were more likely to have paging space >= >real storage. But even there, we've seen >1TB LPARs with with only a few >hundred GB of paging space, including SCM. > >Of course it is also fairly common for those large memory systems to be >running with large amounts of that memory being available. > >---------------------------------------------------------------------- >For IBM-MAIN subscribe / signoff / archive access instructions, >send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
