Berry, Allan,

Thanks, the sizing is not the problem. I have historical peak
utilizations and size the new page configurations to be filled for about
15% with these values.

I am more unsure about the number of page datasets which relates
directly to the amount of parallel I/O 's ASM is able to do, as I
calculated below. What is helpful for performance and what is
unrealistic: 10, 20, 40, 80?

Kees.

-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On
Behalf Of Barry Merrill
Sent: Friday, November 09, 2012 15:22
To: [email protected]
Subject: Re: Paging configuration recommandation on modern Dasd.

You can calculate the percentage of peak slot utilization across time
from your TYPE71 data.
The MXG variable SLOTUTIL in TYPE71 dataset is calculated as
   IF SLOTLOMN GT 0 THEN SLOTUTIL=100*(SLOTLOMN-SLOTUNMN)/SLOTLOMN;
where SLOTLOMN is SMF71MNA and SLOTUNMN is SMF71MNU.

Then compare your values with the 25% to 33% recommended peak
utilization for the contiguous slot allocation algorithm to find free
slots.

Barry Merrill

Herbert W. Barry Merrill, PhD
President-Programmer
Merrill Consultants
MXG Software
10717 Cromwell Drive
Dallas, TX 75229-5112
214 351 1966 tel
214 350 3694 fax
http://www.mxg.com
[email protected]

MXG Support:   [email protected]
MXG Admin:      [email protected]

Standard Answers: http://www.mxg.com/administration
What's Supported:   http://www.mxg.com/changes


 


-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On
Behalf Of Vernooij, CP - SPLXM
Sent: Friday, November 09, 2012 3:08 AM
To: [email protected]
Subject: Paging configuration recommandation on modern Dasd.

Hello,

 

We are implementing a DS8800 with Hyperpav and like to give ASM the best
paging configuration. However, the recommendations in Initialization and
Tunig Guide are outdated, speaking of 3380 devices, Seek penalties,
dedicated devices, channels and control units and the Suspend/Resume
logic.
Occasionally PAV is mentioned, as well as z/OS 1.8, where the
Suspend/Resume is no longer used, without explaining the consequences.

 

There is no good recommendation how to set up a good paging
configuration on a  modern DS8800 device, nor does it explain the
consequences of Hyperpav and WLMPAV set to NO in relation with OA32453
where ASM is still building a " I/O infrastructure" that utilizes
Hyperpav. Nowhere is explained what this infrastructure looks like. From
conversations with Greg Dyke when he was the expert in that area, I know
that in the WLM managed PAV environment ASM reserved 2 access paths to
each page dataset, resulting in 2n-1 aliases dedicated to a paging
volume. Is this still done so in the Hyperpav situation?

 

Our production Sysplex has 10 LCUs on the DS8800 and is connected with 8
Ficon channels. Hyperpav can select alias devices within an LCU, not
over LCUs.

I can allocate 10 page volumes, 1 per LCU, with 1 local page dataset per
volume. This would give ASM 20 access paths to its paging configuration.


I can allocate 2 page datasets on each volume, giving ASM 40 access
paths to its paging configuration. Or 60 or 80.

However, this all has to be handled by the 8 Ficon channels.

 

How do I determine the optimum? I know page-in is hardly a performance
factor these days, but page-out bursts from large dumps can impact
performance, if not handled rapidly.

 

Are there any ASM experts willing to elaborate on this? And possibly
update the Initialization and Tuning Guide for modern Dasd devices?

 

Thanks,

Kees.

 

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this e-mail or any attachments, nor responsible for any delay in receipt. 
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