True, but
still not relevant to the problem. VM:Secure is not installed on the particular
system. If it had been, the symptoms would have been different – the old PARM
extents would have been restored.
Regards,
Richard Schuh
-----Original Message-----
From: The IBM z/VM Operating
System [mailto:[EMAIL PROTECTED]On
Behalf Of O'Brien, Dennis L
Sent: Monday, October 30, 2006
3:28 PM
To: IBMVM@LISTSERV.UARK.EDU
Subject: Re: Corrupted IPL Record
I think Mike meant to say that when
VM:Secure starts up, it reads the allocation bit map of the volume that
has the object directory, not the source directory. The two are not
necessarily on the same volume.
Dennis O'Brien
There are 10 kinds of people in the world; those that understand binary and
those that don't.
From: The IBM z/VM Operating
System [mailto:[EMAIL PROTECTED] On
Behalf Of Mike Walter
Sent: Monday, October 30, 2006
13:02
To: IBMVM@LISTSERV.UARK.EDU
Subject: Re: [IBMVM] Corrupted IPL
Record
Were you running
VM:Secure on that system? Are the DRCT cylinders on that IPL DASD?
If so, this may help.
When VM:Secure
starts up, it reads the whole allocation bit map of the DASD with the source
directory minidisk (usually: VMSECURE 01B0). Each time VM:Secure rebuilds
the object directory cylinders (msg: "VMXRXB0740I The dynamic REBUILD has
completed. Directory maintenance activity will now resume.") it
completely re-writes ALL of the allocation bitmap (as it was when VM:Secure
came up) from its cached copy, except for updates to the bits in the DRCT cyls.
That bit us
(excuse the pun) a couple Sunday IPLs in a row when the newly expanded PARM disk
kept getting changed back to its old size. The back end of the newly
updated SYSTEM CONFIG happened to have 4K blocks allocated on the new
cylinders. When VM:Secure re-wrote the PARM allocation map size/location
(begin location did not change, just the end), it chopped off the last half or
so of the SYSTEM CONFIG. CP happily came up without error because the
truncation just happened to be between SYSTEM CONFIG statements. To
diagnose it, I wrapped SYSTEM CONFIG with confirmatory messages issued as it runs:
Say
"Beginning: 'SYSTEM CONFIG' from MAINT's CF1 disk..."
TOLERATE_CONFIG_ERRORS NO
... rest of
statements...
Say
"Completed: 'SYSTEM CONFIG' from MAINT's CF1 disk."
Be careful of
"TOLERATE_CONFIG_ERRORS NO". Don't just drop it in without
trying it live. There are non-syntactical errors which will pass CPSYNTAX
(everyone DOES run CPSYNTAX **EVERY TIME** after changing SYSTEM CONFIG,
right?), but will cause an IPL error. In our case, the missing 'Completed'
statement confirmed the suspicion. And... explained why the system came
up so half-configured (missing the last half or so of SYSTEM CONFIG).
After reporting
it to CA, they said they would update the doc, showing how VM:Secure can cause
these sorts of problems.
By chance, I had
a conversation with the CPSYNTAX developer about an open PMR just last week.
I suggested some type of new statement pairs which, if present, must BOTH
be present as the first and last non-comment records in SYSTEM CONFIG (and
perhaps IMBED files) to diagnose just this sort of error.
Mike Walter
Hewitt Associates
Any opinions expressed herein are
mine alone and do not necessarily
represent the opinions or policies
of Hewitt Associates.
"Schuh,
Richard" <[EMAIL PROTECTED]>
Sent by: "The
IBM z/VM Operating System" <IBMVM@LISTSERV.UARK.EDU>
10/30/2006 02:32 PM
Please respond to
"The IBM z/VM Operating System" <IBMVM@LISTSERV.UARK.EDU>
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Corrupted IPL
Record
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If this shows up
twice, I apologize. I first sent it 2 hours ago and it hasn't hit the archives
as yet.
Over the weekend, we upgraded our final system to 5.2. As a part of the
migration, we changed old PARM extents to PERM and allocated new PARM extents.
When we tried to ipl the system, there were errors that led me to the
conclusion that the IPL program had been corrupted. Using DDR on another
system, I observed that record 0 0 2 had been completely wiped out. There were
a few scattered bits that were not 0 in the first 100-200 bytes, nothing that
was any kind of pattern, and the rest of the record was all 0. Records 1, and
3-6 were all as they should have been. I had to run SALIPL to fix the IPL
program.
I am not blaming CPFMTXA ALLOCATE because I think it highly unlikely that
it was the cause. I suspect that something else happened between the previous
IPL and yesterday's failed attempt. Has anyone else seen this kind of
corruption or are we, once again, unique?
Regards,
Richard Schuh
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