Catherine,
I don't think your understanding of SHARE is backwards, but your
expectation of what the performance manager will do might be. I suspect
it's trying to keep heavy CPU users from hogging the processors.
To get back to the original question, Jim, I think you need to describe
what the z/VSE guests are doing. If they're supporting interactive users
(e.g., CICS), you'd want one answer from the assembled masses. If they're
true batch workloads, the answer should be quite different. Since your
system's perceived responsiveness likely depends on how quickly TCPIP (and
VTAM) gets serviced, a high share is called for. In your situation, is the
same true for RSCS? Regardless, my experience with the conventional wisdom
of whether to use relative or absolute shares is dated, so I'll leave
detailed recommendations to those with more recent experience.
Marty Zimelis
On Mon, Feb 7, 2011 at 2:13 PM, McBride, Catherine <cmcbr...@kable.com>wrote:
> A while ago a very experienced VM person from IBM suggested that we not
> use ABSOLUTE unless you "absolutely" must cap off a guest to keep it
> from running away with your real processors. We used that setting on
> our test system only.
> Our VSE TOR and VM guest TCPIP both had high relative shares (10000
> versus 3000 for regular production guests).
> Then we started using a performance manager feature of VM Toolkit, it
> managed share values for us.
> It set everything the same after VM IPL, but by the end of a normal
> production day our busiest guests had dropped to the lowest relative
> share, the ones seldom used had the highest. Meaning my understanding
> of how relative share worked was backwards or the gizmo in VM Toolkit
> was. Hopefully Alan or Kris will expound.
>
>
> -----Original Message-----
> From: The IBM z/VM Operating System [mailto:IBMVM@LISTSERV.UARK.EDU] On
> Behalf Of Hughes, Jim
> Sent: Monday, February 07, 2011 12:57 PM
> To: IBMVM@LISTSERV.UARK.EDU
> Subject: SET SHARE ABSOLUTE/RELATIVE
>
> I've read the CP COMMAND manual and the PERFORMANCE manual regarding the
> SET SHARE command and how it works.
>
> Would someone care to comment on how you have used them for your z/VSE
> production and guest machines?
>
> What would suggest for TCPIP/RSCS/VTAM SET SHARE values?
>
> Thanks in advance.
>
>
> ____________________
> Jim Hughes
> Consulting Systems Programmer
> Mainframe Technical Support Group
> Department of Information Technology
> State of New Hampshire
> 27 Hazen Drive
> Concord, NH 03301
> 603-271-5586 Fax 603.271.1516
>
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