We run two sysplexes of about 12 LPARs each (NonProd vs Prod). Both plexes have a single mcat shared across the plex (but not between plexes). We've upgraded these from release to release over the last 10 years and never had to use a second master catalog. In fact, I just checked our NonProd mcat and it was created on 2007.005. We use a single SYSRES with its own catalog, which resides on the SYSRES. The SYSRES is swapped every month for a new one, which is how we introduce maintenance, or even upgrades.
I've seen no down sides to a single mcat for our setup, but as others have noted, it will depend on the role of each system in the plex. For our setup all LPARs serve the same purpose, just for different application instances. Bart -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Allan Staller Sent: Tuesday, November 22, 2016 8:59 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Catalogs in a SYSPLEX " Prior to this job I worked at a shop where we supported sysplexes from a single system to up to 10 LPARs in a single sysplex. The master catalogs were not shared , I think I would put forth one big reason for not sharing the master catalog, would be system upgrades, when we went through the z/OS upgrades, there were times where SYS1. Level data sets location changed from one release to the next and the catalog needed to point to the new location for the new release. We would upgrade one LPAR at a time in a sysplex, which was once a week, so it would be several weeks to complete a sysplex." This is a non-starter. As far as I am concerned, everything that can be shared should be shared (Two of anything that do not agree worse than nothing). If you go with separate MCATS, you must spend a great deal of time ensuring they are in sync w/each other. Sure, you need multiple MCATs during the upgrade cycle, but when all is done, there should be only one MCAT -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Nims,Alva John (Al) Sent: Monday, November 21, 2016 3:44 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Catalogs in a SYSPLEX We currently have a 2 LPAR sysplex and the master catalog in not shared. Prior to this job I worked at a shop where we supported sysplexes from a single system to up to 10 LPARs in a single sysplex. The master catalogs were not shared , I think I would put forth one big reason for not sharing the master catalog, would be system upgrades, when we went through the z/OS upgrades, there were times where SYS1. Level data sets location changed from one release to the next and the catalog needed to point to the new location for the new release. We would upgrade one LPAR at a time in a sysplex, which was once a week, so it would be several weeks to complete a sysplex. I think there are a lot of questions you have to ask yourself about how you are going to handle the sysplex and what you are going to keep in the master catalog, besides SYS1. Note: I believe System Symbols are your friend when setting up the catalog, for both data set names and VOLSER. Al Nims Systems Admin/Programmer 3 UFIT University of Florida (352) 273-1298 -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Travis Sent: Monday, November 21, 2016 3:54 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Catalogs in a SYSPLEX We are creating a SYSPLEX of two systems and there seems to be some debate about using a single shared master catalog or multiple master catalogs on each system. The IBM manuals recommend a single shared master catalog but our CE has been advocating multiple catalogs. What are the pros and cons of running each? We have two identical systems in the PLEX and for right now there is no plan to add more, however that could change at any time in the near future. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
