To elaborate a bit on the possible technical reasons why z/OS 1.12 probably won't work on an IBM z14 machine, even if you've applied every PTF you can lay your hands on to z/OS 1.12, the z14 is the first machine model to drop ESA/390 IPL support. As background, when IBM introduced z/Architecture (64-bit) support in z/OS (all the way back when z/OS was born), the first major step was to engineer z/OS so that it would still start the IPL process in ESA/390 mode, as in OS/390, but then it would switch to z/Architecture mode if available. Up through and including z/OS 1.5 the operating system could run on either ESA/390 or z/Architecture machines. If z/Architecture was available, it would switch into that mode automatically.
IBM also offered some add-on software called the "z/OS Bimodal Migration Accommodation" for those early releases of z/OS up through 1.5. That add-on software would force z/OS to remain in ESA/390 mode on z/Architecture machines. >From z/OS 1.6, IBM dropped support for continuing the IPL and running z/OS in ESA/390 mode. The z/OS-initiated switch early in the IPL to z/Architecture mode became mandatory. z/OS 1.6 was the first z/OS release that could only run on z/Architecture machines, and (after the early IPL phase) it always ran in 64-bit mode. The z14 dropped support for ESA/390 IPL, so any operating system that starts its IPL in ESA/390 (31-bit) mode doesn't work on that machine model, with one caveat that I'll explain in a moment. As far as I know IBM only backported pure z/Architecture IPL to z/OS 1.13 (under extended support) and higher, not to z/OS 1.12 or prior. OK, here's the caveat. As further background, z/VSE underwent a similar evolution in how it IPLs. z/VSE 5.2 and above will IPL on IBM z14 machines even without any PTFs (although PTFs may very well be recommended for other reasons). IBM developed a PTF for z/VSE 5.1 to allow that release to IPL on z14 machines, to be "z/Architecture clean" as it were. But for the z/VSE 4.x releases (and prior), no go. IBM never developed PTFs to retrofit z/Architecture IPL from the very start of the IPL process to any of the z/VSE 4.x releases. However, although all z/VSE 4.x releases are out of support (and have been for years now), those releases are known to be able to IPL on an IBM z14 machine as z/VM guests, not in LPARs. In z/VM you have to use SET MACH ESA to make that work. Will z/OS 1.12 run as a guest under z/VM on an IBM z14 machine in similar fashion (SET MACH ESA)? You're welcome to try provided you've got the right licenses. If you decide to do that you should be fully aware that it's unsupported, and (if it works) you would only want to run that way on a very short term basis for migration purposes only, to help get up to a supported z/OS release. If you don't have a z/VM license, IBM offers sub-capacity z/VM licensing. You can license as little as one engine for z/VM if you wish. For example, if you have an IBM z14 ZR1 capacity model U03, that machine has 3 general purpose engines. You can license one, two, or all three of them for z/VM, as you wish, and then as long as you configure your z/VM LPAR(s) consistent with your licensing (and collect and keep the sub-capacity reports if you're licensing fewer than 3 engines), you're fine. You may also wish to check with your "friendly IBM representative" to inquire about a z/VM evaluation license which might be available under certain circumstances, and if this bit of speculation about z/OS 1.12 has any merit to help you upgrade. -------------------------------------------------------------------------------------------------------- Timothy Sipples IT Architect Executive, Industry Solutions, IBM Z & LinuxONE -------------------------------------------------------------------------------------------------------- E-Mail: [email protected] ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
