in large part coded in good old assembler
language. :-)
Bill Holder, Senior Software Engineer
IBM z/VM Development, Memory Management, Endicott, NY
Phone: 607-429-3640IBM TieLine: 620-3640
for the
product, over 2 million
just for CP. It doesn't give a breakdown by source language.
Bill Holder, Senior Software Engineer
IBM z/VM Development, Memory Management, Endicott, NY
Phone: 607-429-3640IBM TieLine: 620-3640
, there
have always seemed to be more pressing needs.
Bill Holder, Senior Software Engineer
IBM z/VM Development, Memory Management, Endicott, NY
Phone: 607-429-3640
, I hate
to try to give general advice without knowing specifics,
and this isn't really the best place to have that detailed
discussion. All that said, if increasing your memory
within the supported range introduces any new problems,
certainly let us know through normal support channels.
- Bill
Scott, where did you get those numbers? The maximum
amount supported is correct at 256GB, but the enforced
cap is at 512GB, not 1TB. Are you perhaps thinking
instead of the maximum guest size on a particular
machine?
- Bill Holder, z/VM Development, IBM Endicott
On Mon, 11 Oct 2010 09:50
of the concerns raised here.
- Bill Holder, z/VM Development, IBM Endicott
On Mon, 11 Oct 2010 15:07:29 -0600, Scott Rohling scott.rohl...@gmail.co
m
wrote:
I got them from Bill B's 'VM Limits' presentation ..512GB for z9 --
1TB for z10
http://www.vm.ibm.com/devpages/bitner/presentations
to a degree that
is more manageable and can be tuned around.
We understand the need to increase the supported
storage size above the current 256GB limit.
- Bill Holder, z/VM Development, IBM Endicott
On Mon, 11 Oct 2010 17:00:36 -0400, Martin, Terry R. (CMS/CTR) (CTR)
terry.mar...@cms.hhs.gov
, didn't think that
mattered). Anyway, it's out there now. Let us know if
there are any further questions or clarifications needed.
- Bill Holder, z/VM Development, IBM Endicott
On Mon, 11 Oct 2010 16:35:04 -0500, Bill Holder hold...@us.ibm.com wrot
e:
...(bulk of post deleted)...
Bill
developer, I am not officially speaking for
architecture, hardware design, or IBM as a whole.
- Bill Holder, z/VM Development, IBM
I think the main intent was to reassure folks that the risk of encounteri
ng
the problem in most normal production environments is quite small. Or in
other words, don't panic. Still, of course, we recommend applying the
PTF,
especially on systems that page heavily.
- Bill Holder, z/VM
paging, PGMBKs that are less frequently used will have been paged out,
potentially making more room for user pages. So it could be that lower
storage utilization is actually a contributing factor to larger dump size
.
We'd need dumps of the two systems to determine if that's a factor.
- Bill
Correct, though redefining virtual machine storage to a different size
performs a reset clear function on the virtual machine, which could well
help clear up the problem.
But as Alan says, this isn't typically something a customer can unravel
looking at the system from the outside.
- Bill
machine wouldn't clear that, I don't think.
- Bill Holder, z/VM Development, IBM
On Wed, 16 Dec 2009 12:57:40 -0600, Bill Holder hold...@us.ibm.com wrot
e:
Correct, though redefining virtual machine storage to a different size
performs a reset clear function on the virtual machine, which could
storage dynamically - we only allow adding, not removing, stora
ge
dynamically).
Also, these enhancements are available only in z/VM 5.4.0 and above.
- Bill Holder, z/VM Development, IBM Endicott
On Tue, 10 Nov 2009 09:30:41 -0500, Alan Altmark alan_altm...@us.ibm.com
wrote:
On Monday, 11/09/2009
z/VM does not currently support the Enhanced DAT Facility. And it's not
quite as simple as improves performance. There are tradeoffs involved,
and it's not exactly a small undertaking.
- Bill Holder, z/VM Development, IBM
Hi,
I have a zTPF guy who tells me that z/TPF will support
No, neither guest support nor host exploitation is included in current
versions of z/VM.
- Bill Holder, z/VM Development, IBM
On Fri, 30 Oct 2009 15:36:52 -0400, Neale Ferguson ne...@sinenomine.net
wrote:
Can guests use it under z/VM?
On 10/30/09 3:33 PM, Alan Altmark alan_altm...@us.ibm.com
accidentally opened and left open, I think
that would be a more fair analogy. Quibbling over details,
perhaps, but there is an important difference.
On Fri, 18 Sep 2009 10:11:58 -0400, David Boyes dbo...@sinenomine.net w
rote:
On 9/18/09 9:32 AM, Bill Holder hold...@us.ibm.com wrote:
That is indeed
something suicidal, but that's a design and requirements question, not a
defect question.
- Bill Holder, z/VM Development, IBM
On Thu, 17 Sep 2009 17:36:44 -0400, David Boyes dbo...@sinenomine.net w
rote:
On 9/17/09 2:16 PM, Adam Thornton athorn...@sinenomine.net wrote:
Administrator typo
a requirement.
- Bill Holder, z/VM Development, IBM
On Fri, 18 Sep 2009 10:11:58 -0400, David Boyes dbo...@sinenomine.net w
rote:
...
I think we're all in violent agreement on that point. Now, the question
is
what is the best way to put a safety on that gun?
=
===
Is this a
I don't entirely agree. The action of the guest did not cause harm
to CP, it was the action of the operations staff which did. This
is not a denial of service case that I can see.
Bill Holder
z/VM Development, Memory Management team leader, IBM
On Tue, 15 Sep 2009 09:59:09 -0700, Schuh
to
see a dump of the system in question to confirm this hypothesis,
however.
Bill Holder
z/VM Development, Memory Management team lead, IBM
can do, generally, and they all have to be protected.
On Thu, 17 Sep 2009 09:23:11 -0700, P S zosw...@gmail.com wrote:
On Thu, Sep 17, 2009 at 9:14 AM, Bill Holder hold...@us.ibm.com wrote:
I don't entirely agree. The action of the guest did not cause harm
to CP, it was the action
. Note that I'm not
saying it's not APARable, however.
Regards,
- Bill Holder
On Thu, 17 Sep 2009 10:21:05 -0700, Schuh, Richard rsc...@visa.com wrot
e:
An IPL isn't an action? True, the guest was not aware that it would harm
the system, but absent that action by the guest, there would not have
or malicious.
Regards,
- Bill Holder
On Thu, 17 Sep 2009 10:48:53 -0700, Schuh, Richard rsc...@visa.com wrot
e:
I don't think you can differentiate between the root cause and the
immediate cause when it comes to security and integrity. You may not
necessarily be able to detect the root cause, but you must
on the drained volume would drop to zero.
- Bill Holder, z/VM Development, IBM Endicott
On Tue, 10 Feb 2009 09:04:51 -0500, Martin, Terry R. (CMS/CTR) (CTR)
terry.mar...@cms.hhs.gov wrote:
...
2) I believe that some of the paging slots
are old data in other words the pages are not going away after a task is
complete how can I research this. The Linux guests
state transitions, and such pages will tend to rema
in
in place on paging space for long periods of time.
- Bill Holder, z/VM Development, IBM Endicott
but referenced previously pages).
More than anyone ever wanted to know, I'm sure. ;-)
- Bill Holder, z/VM Development, IBM Endicott
to hold the entire
workload, but to also leave enough breathing room in terms of contiguou
s
available sets of paging slots (think entire tracks or more) to allow the
block paging algorithms to work effeciently.
- Bill Holder, z/VM Development, IBM Endicott
). The only reason we recommend not to do it is t
o
avoid any confusion for the one instance where cylinder 0 would be a prob
lem
(and that is tdisk). Having cylinder 0 allocated for paging is not
contributing to any of the observed symptoms (if it was properly formatte
d
first).
- Bill Holder, z
and EREP message
s.
In my experience, such paging errors are overwhelmingly caused by lack of
(or improper) formatting, with minidisk overlays being a distant second,
and
actual disk hardware problems a very far distant third.
- Bill Holder, z/VM Development, IBM Endicott
and VM64510 come to mind) that could have caused some changes, I
'll
have to check in to the contents of those RSUs and get back to you later.
- Bill Holder, z/VM Development, IBM Endicott
the sort
of
your mileage may vary case where the measuring approach of course has
immense value.
- Bill Holder, z/VM Development, IBM Endicott
worth). I'm actually somewhat surprised you didn't run into one of the
other problems I mentioned (FRF002, PGT004, SXP004) with that much
unformatted paging space.
- Bill Holder, z/VM Development, IBM Endicott
possible it's an example of the issue I mentioned, but it's also
possible that 5.4.0's decision might actually be a better overall tradeof
f.
- Bill Holder, z/VM Development, IBM Endicott
to get and apply VM64510, then, and see how t
hat
affects things. In the meantime, yes, you do want to adjust your setting
s.
As long as you don't exceed the values you were typically seeing on 5.3.
0,
that shouldn't affect other processes appreciably.
- Bill Holder, z/VM Development, IBM
system private state, which may have
been captured in that interval. Were vdisks being detached or
vdisk users logging off right about then?
- Bill Holder, z/VM Development, IBM
I should have added that this is how it works in z/VM 5.2.0 and newer
releases. z/VM 5.1.0 and older still use the old FRMTE based locking
scheme, and there's no host logical / host real differentiation, so there
's
only one check, FRMCPLOK.
- Bill Holder, z/VM Development, IBM
On Fri, 12 Dec
PGSD98
LK
for Diag x'98' locking).
Yes, the PGMBK stays resident as long as the page stays locked (in some
cases, even after the virtual megabyte has been released).
- Bill Holder, z/VM Development, IBM
On Thu, 11 Dec 2008 01:05:47 +0100, Rob van der Heij [EMAIL PROTECTED]
wrote:
On Thu
Dave, are you looking to unlock just a subset of what was locked, or all
of
them? If you just want to unlock everything, a single UNLOCK command
covering all the guest's storage (or two, if pages were explicitly locked
to
both real and logical) will do it.
- Bill Holder, z/VM Development
to check
multiple places to determine whether an individual page was locked by com
mand.
- Bill Holder, z/VM Development, IBM
of anything better than trial and error for doing the UNLOCKs. IND
USER will give the number of locked pages (the EXP option will differenti
ate
locked to real vs. locked to logical), but I'm not aware of anything tha
t
will provide the addresses of the locked pages.
- Bill Holder, z/VM
performance and throughput whenever the system is paging, and if bad enou
gh,
can lead or contribute to abends of its own (e.g., FRF002).
- Bill Holder, z/VM Development, IBM
, 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
dense or sparse the guests' stor
age
reference patterns tend to be can greatly influence the degree to which t
he
constraint will be an issue for a given total virtual storage size. I'm
not
sure if we even have typical or average numbers, but I can ask around.
- Bill Holder, z/VM Development
customers were to ask for it to
be
made a priority over other functions already being requested.
- Bill Holder, z/VM Development, IBM
far that would go towards
addressing Richard's needs, though. Still, it would allow them to make s
ome
sort of use of the otherwise idle storage.
- Bill Holder, z/VM Development, IBM
On Wed, 6 Aug 2008 08:50:31 -0700, Schuh, Richard [EMAIL PROTECTED] wrote
:
How long of a period is 24 X 7 X 365? ...
Regards,
Richard Schuh
=
===
I always thought it meant planned outages on Leap Days! %-)
- Bill
restrictive,
requiring pre-planning and definition of the area subject to later remova
l.
Quite a lot of work, and more than a few nasty complications, either way.
- Bill Holder, z/VM Development, IBM
On Tue, 29 Jul 2008 16:17:15 -0500, Bill Holder [EMAIL PROTECTED] wrot
e:
To address the question of adding Linux real memory dynamically:
The z/Linux support for dynamic addition of real memory has been provide
d to
the open source community fairly recently. (I don't know the exact date
community and the commercial distributors of Linux.
There is no support for dynamically adding real memory to z/VM itself or
dynamically increasing the guest real memory (that is, DEF STOR
memory) for guest of z/VM in any announced release of z/VM.
- Bill Holder
z/VM Development, IBM
n
and actual data movement.) Worse, paging using up spool space will almos
t
certainly lead to a PGT004 hard abend, whereas spool using up spool space
normally just leads to spool files being closed and new writes lost.
- Bill Holder
z/VM Development, IBM
by one user at a time, and it i
s
frequently purged and then reloaded, the initial page fault block reads f
rom
spool might show up like this.
- Bill Holder
z/VM development, IBM
multiple dump
files with the same filename and different filetypes, then dataspaces did
not get dumped.
- Bill Holder
z/VM Development
.
- Bill Holder
z/VM Development, IBM
ose
spaces might be getting included.
- Bill Holder
z/VM Development, IBM
On Fri, 9 May 2008 16:45:34 +0200, Rob van der Heij
[EMAIL PROTECTED] wrote:
...
The system is not memory constrained at all, and does not page. So
there is only one page out on DASD, so I know who owns it. If you
through all spaces (for the system and for all users),
and
only ever find one page on DASD total, then you can safely assume it's th
e
one, but otherwise, I don't see how it helps.
- Bill Holder
z/VM Development, IBM
On Fri, 9 May 2008 06:47:03 +0200, Rob van der Heij
[EMAIL PROTECTED] wrote
to find and migrate such pages
long ago.
Also, it's not at all a safe assumption that the offending page is a us
er
or guest page, it could just as easily be a CP page for some pageable CP
utility space.
- Bill Holder
z/VM Development, IBM
On Wed, 7 May 2008 21:44:45 -0400, Marty Zimelis
or DCSS, it reverts back to the initial read from SPOOL state again
.
- Bill Holder
z/VM Development, IBM
On Wed, 7 May 2008 22:35:18 -0400, Stracka, James (GTS)
[EMAIL PROTECTED] wrote:
Martha,
Others have suggested labor intensive ways to find this. I know of no
program to do it. Perhaps
could well be an NSS/DCSS page.
- Bill
- Bill Holder
z/VM Development, IBM
On Thu, 8 May 2008 13:10:23 -0400, David Kreuter [EMAIL PROTECTED]
om
wrote:
read-only nss/dcss pages are most certainly paged out. They are not
reloaded from spool.
read-write nss/dcss pages different story
.
- Bill Holder, z/VM Development, IBM
On Fri, 4 Jan 2008 14:03:33 +0100, Rob van der Heij [EMAIL PROTECTED] w
rote:
On Jan 4, 2008 1:32 PM, David Boyes [EMAIL PROTECTED] wrote:
Did you recently add some page space to the system, or possibly
overlapped some of your paging or spool space
to offer it for fixtest / circumvention for any
customers who would like it, especially those who have already experience
d
symptoms. The official APAR is working its way through the process, we
expect the official PTF to be available within a week or so.
- Bill Holder, IBM Endicott, z/VM
VM64297 has closed and the corresponding PTF, UM32197, is now available.
- Bill Holder, IBM Endicott, z/VM Development and Service
=
So, how did the upgrade with the fixtest go? Does silence indicate succe
ss?
- Bill Holder, IBM Endicott, z/VM Development and Service
of the
month, 10/31, which I'm fairly confident we'll make.
- Bill Holder, IBM Endicott, z/VM Development and Service
and unusually
high paging activity right before or during the problem period.
- Bill Holder, IBM Endicott, z/VM Development and Service
it'
ll
get smoothed out shortly. If there are any other examples that need
clarification or rewording, though, please bring them up and we'll do our
best to get them fixed up.
- Bill Holder
z/VM Development Service
't
be able to figure out without the dump.
Bill Holder
z/VM Development, Memory Management team lead
IBM Endicott
On Tue, 8 May 2007 00:57:15 -0400, Alan Altmark [EMAIL PROTECTED]
wrote:
On Tuesday, 05/08/2007 at 12:09 ZE8, Mikhael Ramirez Joaquin
[EMAIL PROTECTED] wrote:
The message left
it becomes available (which should not be much
longer). There are still some open questions whether there are any DB2
functional exposures even with these two fixes applied, and we are active
ly
working on trying to answer those questions.
Regards,
- Bill Holder, z/VM Development and Service, IBM
The QUERY and SET MEMASSIST commands will not be available until VM63856
is
available and applied.
- Bill Holder, z/VM Development, IBM Endicott
On Wed, 13 Dec 2006 11:25:09 -0600, Tom Duerbusch
[EMAIL PROTECTED] wrote:
I see in the z/VM 5.2 manuals some new commands. Many work under
MAINT
it is, a
s
the alternative fixes are a lot more complicated). The only concern we h
ave
with the circumvention isn't functional, it's the potential impact on
performance of holding a share of one of the locks involved (VMDPTIL) for
a
longer duration.
- Bill Holder, z/VM CP Development, Storage
On Mon, 27 Mar 2006 16:11:09 -0600, Bill Holder [EMAIL PROTECTED] wrot
e:
There are two aspects of the problem, only one of which is directly Diag
nose
x'10' / release processing related. The other aspect has to do with
handling of the logically 0 page state created by Diagnose x'10', when
of the
problem occurring for SFS with dataspaces (and the exposure isn't dataspa
ce
specific), or anything other than DB2, so I'm fairly confident your syste
m
will not experience it.
- Bill Holder, IBM z/VM CP Development, Storage Management
On Mon, 27 Mar 2006 14:50:50 -0800, Schuh, Richard [EMAIL
Actually, Alan, it's the HRM003 after the DB2 abend, not the FRF002, that
VM63978 should fix. The FRF002 is fixed (circumvented) by the DB2 APAR y
ou
previouly applied, and we're still investigating the CP aspects under APA
R
VM63975 (yet another nearby number).
- Bill Holder, IBM z/VM
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