I remember IBM sent out an APAR for VM/SP to fix the problem. I would hope the code has been
included in every VM since then.
Bill Holder wrote:
On Thu, 28 Aug 2008 01:54:51 -0400, Alan Altmark <[EMAIL PROTECTED]
wrote:
...
Look in the archives of this listserver and you will find z/VM Developme
nt
stating that the volume label is safe from CP, even if cyl zero is
allocated as page or spool.
From a system management point of view, however, and for your sanity's
sake, however, I suggest that cylinder zero SHOULD always be allocated a
s
PERM. Adding one additional cylinder will not help the system in any
meaningful way and only serves to create controversy and risk.
So, "someone" is wrong from a technology perspective, but right in terms
of Best Practice.
BTW, CP will happily hand out cylinder 0 to a guest if it is marked as
T-disk. Dumb, perhaps, but true.
Alan Altmark
z/VM Development
IBM Endicott
========================
=========================
========================
For what it's worth, ICKDSF (which CPFMTXA uses) was changed several year
s
ago and no longer permits allocation cylinder 0 as tdisk, though the prob
lem
could still occur with volumes formatted before that change (or by some
other utility).
Page and Spool usage of cylinder 0 has worked properly and been supported
by
the VM/XA -> VM/ESA -> z/VM lineage the entire time I've been with VM (th
at
is, since 1986). In that entire time, I'm unaware of even one problem
involving page or spool usage of cylinder 0 (and I've been the team leade
r /
subsystem owner of the most affected area for 18+ of those years, so I wo
uld
have heard).
Still, as long as there's any risk (with tdisk allocations) and confusion
and misunderstanding, I won't argue with the recommended "best practices"
of
avoiding cylinder 0 simply to avoid having to have these discussions ever
y
few months (or at least, to keep them short).
- Bill Holder, z/VM Development, IBM
--
Stephen Frazier
Information Technology Unit
Oklahoma Department of Corrections
3400 Martin Luther King
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Tel.: (405) 425-2549
Fax: (405) 425-2554
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email: stevef%doc.state.ok.us
