This is a quote from IBM-MAIN, <QUOTE> A z890 is quite capable of running ESA/390 mode LPARs. In fact, every IPL starts out in ESA/390 mode, and then the operating system does a SIGP SARCH into z/Architecture mode if desired.
z890, z990, and z9 machines have a 2-level TLB. Nothing lower than OS/390 2.10 will run reliably on a machine with a 2-level TLB because lower releases than 2.10 do not do some of the necessary TLB purges. I have heard some speculation that you might be able to get around this by running an older MVS under VM, with the following VM trace: #CP TRACE IPTE RUN NOTERM Of course, this would cause some performance degradation, since VM would intercepting and simulating every IPTE for this virtual machine. I don't know of anyone who has tried this. It was just some hall talk with a VM developer. There may be other issues that would prevent an older MVS from running on a modern machine, such as missing support for a larger storage increment size. The storage increment size might also be avoided under VM if the virtual machine does not have too much real storage defined - I think VM simulates the increment size but I wouldn't swear to that. And there may be other issues that I am not remembering. The bottom line is that you won't find anyone who knows for sure. The only way you could find out is to try it. And as others have pointed out, if by "old, old" you mean pre-MVS/XA, you can most definitely forget that. Support for pre-XA architecture was dropped by the 9672 G4 machines (9672-Rx5). Jim Mulder z/OS System Test IBM Corp. Poughkeepsie, NY </QUOTE> This possibly is the "magic command" mentioned below. However, I will state that I would personally NOT try this on a production machine (I am referring to the z/VM LPAR, not just the OS/390 guest, but then I am a little paranoid with production stuff), YMMV. Wayne Driscoll Product Developer NOTE: All opinions are strictly my own. -----Original Message----- From: The IBM z/VM Operating System [mailto:[EMAIL PROTECTED] On Behalf Of Mike Hammock Sent: Wednesday, September 24, 2008 3:56 PM To: IBMVM@LISTSERV.UARK.EDU Subject: Re: Running os/390 as a guest OS/390 2.10 is known to run reasonably well as a guest of a current zVM with no special actions required. OS/390 2.9 (and earlier) has a problem. I don't remember exactly what wait-state it loaded during the IPL, but using normal procedures 2.9 would not IPL as a guest of zVM 5.3 on a z9.. I did get a "magic command" from an IBM friend (who shall remain nameless unless he speaks up) that allowed the OS/390 2.9 system to IPL and run. We did isolate the OS/390 as much as possible (full-pack minidisks instead of dedicated, etc.) Obviously this is very far from 'supported' in any sense of the word, but we do have a one customer running 2.9 and several customers running 2.10 on a z9 under zVM 5.3. I would not want to hazard a guess as to whether 2.8 would be possible... It may also make a difference what type of hardware you are running this on... The above experience is on z9s. It is possible that it would not work on a z10. Mike C. M. (Mike) Hammock Sr. Technical Support zFrame & IBM zSeries Solutions (404) 643-3258 [EMAIL PROTECTED] "Mike Spaniol" <[EMAIL PROTECTED] ckwell.com> To Sent by: The IBM "IBMVM@LISTSERV.UARK.EDU" z/VM Operating <IBMVM@LISTSERV.UARK.EDU> System cc <[EMAIL PROTECTED] ARK.EDU> Subject Running os/390 as a guest 09/24/2008 01:53 PM Please respond to The IBM z/VM Operating System <[EMAIL PROTECTED] ARK.EDU> Hello, May I run OS/390 V2R8 as a guest under any of the supported releases of z/VM? I believe it is unsupported by IBM, but, does it work? OS/390 is unsupported so I don't think I'm any worse off. I'm looking at bringing in a smaller, newer, IBM mainframe and trying to save some money on my IBM monthly license fees. But, I need to support an old guest running OS/390 V2R8. I can't afford to upgrade all the third party software that this guest is using. Mike Spaniol Blackwell Senior Systems Programmer 6024 Jean Road, Building G, Lake Oswego, OR 97035 Tel: +1 503-684-1140 X1397 Fax: +1 503-639-2481 -------------------------------------------------------------------- This email and any attachments contain information from Blackwell which may be confidential, privileged and/or protected by other legal rules. If you are not the intended recipient, you are hereby advised that any disclosure, copying, distribution or use of the contents of this email is prohibited. If you have received the email in error, please notify us by reply email immediately and then delete the email and your reply from your email system. NOTE: Blackwell accepts no liability for the contents of this email. __________________________________________________________ This email may contain confidential and privileged material for the sole use of the intended recipient(s). Any review, use, distribution or disclosure by others is strictly prohibited. If you are not the intended recipient (or authorized to receive for the recipient), please contact the sender by reply email and delete all copies of this message. To reply to our email administrator directly, send an email to [EMAIL PROTECTED]
