Brian, So I get the fervor, but might be a little harsh? By "dataset", not sure he was talking about dataset structure, but maybe the contents of any dataset. For example, and this happened to me, and this all happened within the same z/OS release, but would just as easily occur on a z/OS long jump with no easy way to go back...A year ago, due to SNAFU with IBM hold data being incorrect for certain DFSMSHSM maintenance, a conditioning/toleration PTF was missed. The feature "enabling" PTF was IPL'd into one of systems in the sysplex that shares the HSM CDS's which happily started writing new format data into the CDS. Wasn’t noticed until the next day when data that was migrated on that updated system could not be recalled on a down leveled system, and HSM was taking errors/dumps.
This is just one example In the long jump scenario, that if the need to fall back were to be utilized, HSM functions would be broken. And if HSM was the one doing the CDS backup's recovery of those might be a problem too. This is just one real life example, there could be many more. There is a *risk* of doing the long jump, mostly with regards to ability to fall back, and being honest, in all my years, we have had to fall back maybe one time. Best advice is don’t get into a position where you are out of support. _____________________________________________________________________________________________________ Dave Jousma AVP | Manager, Systems Engineering Fifth Third Bank | 1830 East Paris Ave, SE | MD RSCB2H | Grand Rapids, MI 49546 616.653.8429 | fax: 616.653.2717 -----Original Message----- From: IBM Mainframe Discussion List <[email protected]> On Behalf Of Brian Westerman Sent: Friday, September 6, 2019 3:41 AM To: [email protected] Subject: Re: z/OS 2.1 to 2.4 [EXTERNAL] **CAUTION EXTERNAL EMAIL** **DO NOT open attachments or click on links from unknown senders or unexpected emails** Well, you know what they say about assumptions. That definitely applies to your assumptions here. How did you get into ACM, did you buy a membership or something?:) I really don't mean to sound flippant or like I'm trying to degrade your abilities or anything, but you don't seriously believe all that stuff you wrote, do you? There hasn't been a totally incompatible dataset level change sent out for a good many years, and by that I actually mean so far this millennium), and IBM is not about to change that kind of thing in a simple release change. Something like that would result in a version change at the very least if not a complete OS name change. Remember that this op is converting from 2.1 to 2.4, (and I don't think he means MVS/XA 2.1 to z/OS 2.4, I believe he means z/OS 2.1 to z/OS 2.4), but with the possible exception of ISAM and some old DL/1 structures that would have to be addressed ahead of time even that conversion is doable if you discard the processor change necessary and only count the data. Did you possibly forget that one of the things that sets the IBM mainframe apart from everything else is the VERY long pedigree of backwards compatibility? The whole idea of the way IBM manages z/OS is not going to be placed at jeopardy, just because they want to come out with a new dot.release. :) If it was meant to "scare" the OP into going through a completely unnecessary installation of z/OS 2.2 or 2.3 then you really should be ashamed of that. Almost everything you said was (at best) unwarranted. It was almost like reading something in one of those "this is an example of fake news" sites. If the OP were converting from OS/390 to z/OS 2.4 he could STILL share the dasd. I should know, I still do conversions for people from OS/390 to z/OS 2.x, I did 3 of them just this year, and while the mainframe CPU can't handle the two systems at the same time, the dasd and the datasets do. Doing "long jump" migrations is almost always a hardware issue, not a software or dataset issue. If you want to perform unnecessary installations on your time at your site, that's completely up to you, but when someone asks a serious question and you come up with a bunch of FUD, it just serves to undermine what I thought was supposed to be the purpose of this site, which I had thought was to provide a forum for people to get help and exchange ideas, not to try to scare them with half baked assumptions and leading questions which seem to be written solely for no useful purpose. I am positive that I have likely performed more long jump conversions than you, and I would be willing to bet that I have performed in just the past two years more operating systems conversions period, than you have performed in your entire professional life as a systems programmer, if you even are one, which based on your response I'm not quite certain of. While doing a lot of migrations and conversions doesn't make me perfect, it does mean that I am (a lot) less likely to be wrong about this than you are. Again, I know it sounds harsh, but this is one of my hot buttons. When people try to talk about IBM's N+ "suggestion" as if it's anything other than that, "a suggestion". About 10% of the long jump migrations I have performed were done through IBM for their client sites, not for any of our existing clients. I have yet to have a failure to complete a migration on time and as promised. Again, I'm very sorry if I have insulted you in any way, that was not my intention, but I am really and truly surprised at the lack of restraint and knowledge about what is involved in a conversion or migration or even in simply sharing dasd and other resources shown in your response. So, please excuse my harsh response, but I didn't want the OP to think that you knew anything about what you were saying. While you did phrase everything as if you were merely trying to point out possibilities that I may have overlooked, you were just so far from correct that I could not allow it to go UN-commented upon. Sorry, Brian ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN **CAUTION EXTERNAL EMAIL** **DO NOT open attachments or click on links from unknown senders or unexpected emails** This e-mail transmission contains information that is confidential and may be privileged. It is intended only for the addressee(s) named above. If you receive this e-mail in error, please do not read, copy or disseminate it in any manner. If you are not the intended recipient, any disclosure, copying, distribution or use of the contents of this information is prohibited. Please reply to the message immediately by informing the sender that the message was misdirected. After replying, please erase it from your computer system. 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