On Tue, 22 Aug 2006 16:39:15 -0500, Mark Zelden <[EMAIL PROTECTED]> wrote:
>On Tue, 22 Aug 2006 16:19:06 -0500, McKown, John ><[EMAIL PROTECTED]> wrote: > >>I remember limiting my main production LPAR to less than 2Gig due to >>some RSM problems in the deep, dark past (1.4?). Now that I'm on z/OS >>1.6 and fairly current with maintenance, is there any known gotchas with >>CSTOR > 2Gig? >> > >The deep dark past was OS/390 2.10 running in z/Architecture mode >(which was the first time you could have more than 2G central). >There have been some issues since the start, but most of them were >fixed or had work around. In-real swap at z/OS 1.2 fixed some of >the issues in OS/390 2.10. Some of the problems are / were actually due >to not having enough real storage (spin loops etc;), and the workaround >was coding MCCAFCTH= in IEAOPTxx (until now where a recent APAR sets >this dynamically with some intelligence - see OA14409). > >From day one of 64-bit you had to (at a minimum) take your pre 64-bit >expanded storage amount, add that to your central storage amount and >use that as your starting point. For any decent sized LPAR, that meant >running with more than 2G of central storage. So if running with more >than 2G central was a problem, almost no one would have migrated to >64-bit. > >Don't worry, be happy. It just dawned on me that even though you mentioned RSM, you may be thinking about the issues with programs that used LRA in an LPAR with more than 2G central (0D3 abend). The problems were with some IBM code (IMS, Peter Relson's Module Fetch Monitor for examples) and at least a few ISV products that I remember. Those problems were fixed *a long* time ago. But you are correct that running 64-bit in an LPAR with less than 2G did avoid that problem. That is probably why so many of them turned up. How many sandbox / development / test systems had more than 2G central around the OS/390 R10 time frame? I know at several of the shops I was consulting at around that time, extra stroage was purchased, begged, borrowed, and stolen to try and get a test environment with more than 2G in order to test the migration to 64-bit. Regards, Mark -- Mark Zelden Sr. Software and Systems Architect - z/OS Team Lead Zurich North America / Farmers Insurance Group mailto: [EMAIL PROTECTED] z/OS and OS390 expert at http://searchDataCenter.com/ateExperts/ Mark's MVS Utilities: http://home.flash.net/~mzelden/mvsutil.html ---------------------------------------------------------------------- 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
