I can verify that using
#CP TRACE IPTE RUN NOTERM
does allow a OS/390 2.9 guest to run under zVM on a z9 (whereas it did not
IPL successfully without this command).
I would hesitate to generalize this any further...
Mike
C. M. (Mike) Hammock
Sr. Technical Support
zFrame & IBM zSeries Solutions
(404) 643-3258
[EMAIL PROTECTED]
"Wayne Driscoll"
<[EMAIL PROTECTED]
st.net> To
Sent by: The IBM "[email protected]"
z/VM Operating <[email protected]>
System cc
<[EMAIL PROTECTED]
ARK.EDU> Subject
Re: Running os/390 as a guest
09/26/2008 01:02
PM
Please respond to
The IBM z/VM
Operating System
<[EMAIL PROTECTED]
ARK.EDU>
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: [email protected]
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 "[email protected]"
z/VM Operating <[email protected]>
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
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