On 11/4/2019 9:39 AM, Tom Marchant wrote:
On Mon, 4 Nov 2019 14:04:02 +0000, Allan Staller wrote:
IBM has generally recommended 2:1 virtual to real storage. I have
pushed this to 3:1 without major issues.
The paging subsystem should be configured accordingly page slots
approx. 3x available real.
If you are actually going to be doing serious paging, (> +/- 20 pps)
the local page datasets should not be more that 30% utilized, so 9x
real page slots is appropriate.
Are you suggesting that an LPAR with 10 TB of real memory should have
30 to 90 TB of page space? If my arithmetic is correct, the minimum
number of volumes that could satisfy that is between 545 and 1636
volumes of 3390 model 54.
Do your systems follow the guidelines that you suggest?
I think it is still true that local page data sets should be no more
than about 30% full. IIRC the reason has to do with the probability
that the system will be able to find full tracks to page out to.
Tom,
I posed this same question about 2 years ago. Then I was dealing with
an LPAR with 131GB, so I created a 400GB paging subsystem to handle the
system. Others suggested SCM, but that was not in the budget. If the
10TB is truly fully utilized, then a 30TB paging subsystem makes sense.
Unless I hear differently from IBM, paging rules still apply, even for
10TB systems.
Regards,
Tom Conley
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