On 7/6/2015 9:24 AM, Staller, Allan wrote:
<snip>
I said it's best to use same-size DS & have usage of under 30% (each DS), but
it was rejected as old-recommendation.
</snip>
This is/was AFAIK, the current recommendation.
As to whether the "small" page ds is problem, the answer is "it depends".
Perhaps the people in charge are unaware that this change(resize/drop the
"small" page ds) can be performed dynamically with no observable impact to the
running system.
HTH,
<snip>
A site uses different size local page DS.
say most are 200K TRK , but 1 is 10K TRK.
normal : 15% 70% used
problem: 60-70% 95%
I said it's best to use same-size DS & have usage of under 30% (each DS), but
it was rejected as old-recommendation.
Sometimes they get IRA205I.
MSG actually says:
... When utilization exceeds 30%, the slot allocation algorithms become less
efficient, and may degrade I/O performance.
Is this ROT still apply:
same size local PAGE DS
< 30% used
</snip>
30% for page datasets is not an "old" recommendation, it is still very
much current. Block paging algorithms are SIGNIFICANTLY inhibited once
usage goes above 30%. Your paging datasets should be at least 3X real
memory, so if you've got 8GB real, you should have at least 24G of page
datasets (approx 9 mod-3's). You may not need it for a lot of stuff,
but if you ever get a lot of dump activity, you'll be glad you have it.
Regards,
Tom Conley
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