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. . . J.O.Skip Robinson Southern California Edison Company Electric Dragon Team Paddler SHARE MVS Program Co-Manager 323-715-0595 Mobile 626-543-6132 Office ⇐=== NEW [email protected] -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Mark Zelden Sent: Thursday, April 06, 2017 7:52 AM To: [email protected] Subject: (External):Re: RLS for catalogs On Wed, 5 Apr 2017 18:23:29 +0000, Jesse 1 Robinson <[email protected]> wrote: >I’m curious about using CA MIM Resource Sharing within a sysplex. >Historically I used it in the days before sysplex, before PDS/E, >before other newfangled contraptions that depend on XCF for >serialization. We still use MIA for tape allocation across sysplexes and >across data centers. What does MIM offer for ENQ within a sysplex? If it is a basic sysplex, MIM (with CTCs) runs circles around GRS RING in terms of performance. If you only have 2 systems it probably doesn't matter, but as soon as you have 3 more systems you can really notice the difference. *disclaimer* It has been quite a number of years since I have been at a GRS RING shop with 3 or more systems but I recall a CA-1 scratch run taking many hours due to the cross system ENQs then my client switched to MIM and the scratch run ran in probably half the time. The improvement in time logon to TSO and get to the ISPF main menu was very noticeable. For a parallel sysplex where the scope of sharing is just withing the sysplex, I don't know why anyone would use MIM over GRS these days. Also, with the cheaper cost of ICF engines and inexpensive memory, I would think the cost would at least be similar to licensing MIM. 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
