10TB real 30TB Paging. On Tue, Nov 5, 2019 at 10:35 AM Allan Staller <allan.stal...@hcl.com> wrote: > > I never based my estimates on the amount of real. Only on the Virtual. > > Using our same 10TB system with a 2:1 virtual to real would result in 20 TB > page slots and a 60TB paging subsystem. > > > > -----Original Message----- > From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of > Tom Marchant > Sent: Tuesday, November 5, 2019 8:56 AM > To: IBM-MAIN@LISTSERV.UA.EDU > Subject: Re: How display level of paging? > > On Mon, 4 Nov 2019 17:46:12 -0500, Tom Conley wrote: > > >I posed this same question about 2 years ago. Then I was dealing with > >an LPAR with 131GB, so I created a 400GB paging subsystem to handle the > >system. Others suggested SCM, but that was not in the budget. If the > >10TB is truly fully utilized, then a 30TB paging subsystem makes sense. > >Unless I hear differently from IBM, paging rules still apply, even for > >10TB systems. > > Looking at one of our bigger LPARs here, we have > > 66 GB of storage > 8 local page data sets that fill 3390-9 volumes (total 68 GB) > 264 GB SCM paging devices > > So we are well within what you think is needed. I am not the sysprog here, > but if I was I would not be opposed to reducing it because: > > The local page data sets are all 0% full The the SCM is using 64 M of the 264 > GB > > Admittedly, we are a small shop. We are also a development shop and take a > fair number of SVC dumps. > > Those old rules were from the days when memory was expensive and paging was > common. Back in the 80's it was not uncommon to page at rates of 50 to 100 > pages per second on a machine with 32 to 64 MB of main storage, and have 5 GB > or more of page space utilized. Today, paging, and page space utilization, is > normally much less. > > What I would suggest that you need for page space today is more like the sum > of: > > Maximum virtual storage in use minus real storage, multiplied by 3 and Enough > to support the capture of the biggest possible SVC dump, multiplied by 3. > > I don't remember a time that the recommendation was to size paging subsystems > based upon the amount of real storage on the processor. > Indeed, 30 years ago that would have been wholly inadequate. > > I don't buy the suggestion that an LPAR with 10 TB of storage should have 30 > to 90 TB of paging space. > > I'll close with this observation. A z15 processor can have a maximum of > 40 TB of customer storage. The maximum amount of SCM is 6 TB. You want to > configure your paging subsystem so that paging to DASD is rare, and almost > all paging is to SCM, because SCM is so much faster. > > -- > Tom Marchant > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, send email to > lists...@listserv.ua.edu with the message: INFO IBM-MAIN > ::DISCLAIMER:: > ________________________________ > The contents of this e-mail and any attachment(s) are confidential and > intended for the named recipient(s) only. E-mail transmission is not > guaranteed to be secure or error-free as information could be intercepted, > corrupted, lost, destroyed, arrive late or incomplete, or may contain viruses > in transmission. The e mail and its contents (with or without referred > errors) shall therefore not attach any liability on the originator or HCL or > its affiliates. Views or opinions, if any, presented in this email are solely > those of the author and may not necessarily reflect the views or opinions of > HCL or its affiliates. Any form of reproduction, dissemination, copying, > disclosure, modification, distribution and / or publication of this message > without the prior written consent of authorized representative of HCL is > strictly prohibited. If you have received this email in error please delete > it and notify the sender immediately. Before opening any email and/or > attachments, please check them for viruses and other defects. > ________________________________ > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
-- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
