Note on GBP duplexing: Not duplexing, to my understanding, would force a DB2 group restart after a CF failure.
On the other hand, duplexing GBP's can be expensive. Fortunately, IBM introduced asynchronous duplexing which saves quite a bit of CPU. You just have to make sure your z/OS, CF microcode and DB2 levels support it. Robert Crawford Abstract Evolutions LLC (210) 913-3822 -----Original Message----- From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of Martin Packer Sent: Wednesday, June 21, 2023 4:36 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: [EXT] Re: Coupling Facility Structure Resizing I presented - briefly - on this yesterday at the Munich Resilience/Resiliency conference. Yes, SMF 74-4 tells you what IS - and perhaps tells you stuff to make you resize structures. To the point, though: You need to think through the scenarios - both for memory and CF CPU. For example, you probably aren't going to move XCF structures from a failing CF to a surviving one. Likewise, you might forego duplexing of GBPs or even LOCK1 in an emergency. (A third coupling facility to re-establish duplexing is a luxury many customers don't have.) Yes, you need some margin for growth. But you probably don't need 50% white space in a CF. But, to repeat, do it by walking through the scenarios. And SMF 74-4 is your friend. Cheers, Martin From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> on behalf of kekronbekron <000002dee3fcae33-dmarc-requ...@listserv.ua.edu> Date: Sunday, 18 June 2023 at 06:25 To: IBM-MAIN@LISTSERV.UA.EDU <IBM-MAIN@LISTSERV.UA.EDU> Subject: [EXTERNAL] Re: Coupling Facility Structure Resizing Hi Bill, everyone On top of this, we manually factor for failover, headroom for growth etc. as 20% of current avg/peak (for example), and then allocate 1.2x memory for the CF LPAR itself? In short, how does one go from structure size calculations to CF LPAR memory sizing, in the context of machine or CFCC upgrades. - KB ------- Original Message ------- On Sunday, June 18th, 2023 at 8:05 AM, Bill Neiman <nei...@us.ibm.com> wrote: > The appropriate tool for resizing structures during a migration from one > CFLevel to another is the SIZER utility, which is distinct from CFSizer. > SIZER uses the IXLMG and IXCQUERY APIs to collect structure attribute and > count information from all allocated structures, and then uses the IXLCSP API > to direct structure size computation requests based on that collected > information to all CFs connected to the system from which it is running. You > can download the SIZER package, containing the executable, linkedit JCL, > execution JCL, and a user guide, from the CFSizer alternate sizing techniques > page at > https://www.ibm.com/support/pages/cfsizer-alternate-sizing-techniques. The > utility runs as a batch job or started task. The documentation explains the > use case, procedure for use, and interpretation of the results. Read it > carefully before running the utility. Note in particular that for SIZER to be > helpful during migration, you must run it when both old and new CFs are > installed in the sysplex. > > Bill Neiman > IBM Parallel Sysplex Development > > ---------------------------------------------------------------------- > 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 Unless otherwise stated above: IBM United Kingdom Limited Registered in England and Wales with number 741598 Registered office: PO Box 41, North Harbour, Portsmouth, Hants. PO6 3AU ---------------------------------------------------------------------- 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
