On Thu, 6 Apr 2017 15:56:29 +0000, Jesse 1 Robinson <[email protected]> wrote:
>This goes back several years when CF and memory resources were more expensive >and less flexible than today. Think standalone CF where a memory >upgrade was >a huge PITA. We had one single-system parallel sysplex that I had refrained >from turning over to GRS star. It was only one system, after all, so >what >could be harm in running GRS ring? Star would be a waste of resources, I >thought. > >One particular housekeeping job ran daily in every sysplex. It did a massive >LISTCAT. We noticed that this job ran two or three times longer (!) on this >one >system as compared with other sysplexes that made use of GRS star. I >could not find any plausible difference other than GRS configuration. So on a >hunch I >bit the bullet and implemented GRS star. Sure enough, the elapsed >time for the big LISTCAT job immediately dropped to a value in line with the >other >sysplexes. That's on a system that did not actually share resources >with any other. Not a scientific observation, but I'm as convinced as any UFO >witness ever >was. Wow! I believe you, but I'd love to hear the technical explanation for that from an IBM GRS and/or sysplex guru considering it was a single system. I can only guess that it was just a different code path taken that was more efficient and it didn't have anything to do with delays in propagating ENQs. Or maybe there were reserves involved that went away with GRS STAR, but I wouldn't think so with just a LISTCAT. Going back to the "old days" if you really had a single system you didn't want to gen the DASD as shared and that would avoid RESERVEs from being issued. I'm feeling old now... :-) Regards, Mark -- Mark Zelden - Zelden Consulting Services - z/OS, OS/390 and MVS ITIL v3 Foundation Certified mailto:[email protected] Mark's MVS Utilities: http://www.mzelden.com/mvsutil.html Systems Programming expert at http://search390.techtarget.com/ateExperts/ ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
