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Tunig Guide are outdated, speaking of 3380 devices, Seek penalties,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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