Radoslaw and others, Please consider supporting my idea on the ideas portal.
Better support for multiple master catalogs in a sysplex. https://ibm-z-hardware-and-operating-systems.ideas.ibm.com/ideas/ZOS-I-3890 Lennie Dymoke-Bradshaw https: //rsclweb.com -----Original Message----- From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of Radoslaw Skorupka Sent: 29 November 2023 15:42 To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Page Datasets in User Catalog W dniu 29.11.2023 o 04:56, Mark Zelden pisze: > On Thu, 23 Nov 2023 14:20:51 -0600, Jon Perryman<jperr...@pacbell.net> wrote: > >> On Wed, 22 Nov 2023 22:35:13 +0000, Seymour J Metz<sme...@gmu.edu> wrote: >> >>> I suspect that there was a game of telegraph, whereby crucial details got >>> lost. >>> >>> It is normal to allocate page datasets in a user catalog that will >>> eventually be used as a master catalog. >>> I'm suspicious of the claim that z/OS can use a page dataset that is not >>> in its own master catalog, but I can't rule it out. >> There are definitely crucial details lost. Page and swap are special >> datasets. For instance, a page dataset can be in multiple catalogs (I think >> using recatalog). > Pagespace can be in multiple catalogs (which should be a master to the > system that is using it) via RECATALOG. I think at one time it had to > have a HLQ of PAGE or SYS1 but my memory is fuzzy on that part. I know for a > long time the HLQ doesn't matter at all for pagespace and it could still be > in > multiple catalogs. This also applies to swapspace and VSAM linear ZFS that > is indirectly cataloged. > Any SYS1 VSAM dataset can be in multiple catalogs via recatalog. > > Don't ask me where this is documented now. :) I'm guessing "DFSMS managing > catalogs". I dare to correct the above considerations. 1. Any non-VSAM and non-SMS dataset can be catalogued twice or multiple times. Reason is obvious: there is no backward reference. It is just entry in BCS, which contains DSN, UNIT and VOLSER. 2. VSAM datasets *cannot* be catalogued multiple times. And there is a way to enforce it - VVDS. 3. IBM created exceptions for the 2. but only for SYS1 and PAGE HLQ. Note - this is matter or HLQ, not VSAM type or flavour. In other words one can "multi-catalog" any SYS1.VSAM.DSN regardless of its purpose and any PAGE.VSAM.DSN, also regardless of its purpose. 4. Page dataset is specific kind of VSAM, because it is somehow formatted before use. As one may know DEF PAGE takes significantly more time than regular DEF CL and depends on its size. 5. So, it is still possible to have good reason to create some page datasets, even cataloged in UCAT, but for future use. And future use will require page datasets to be in MCAT. How? a) recatalog. b) my current UCAT is de facto other system's MCAT. Other scenarios may apply. My €0.02 -- Radoslaw Skorupka Lodz, Poland ---------------------------------------------------------------------- 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
