> All data sets are the same size at 5,008 cylinders, half of a 3390-9. 
> 
> LOCAL     55%   OK  1208  SYS1.PAGELOC0
> LOCAL     34%   OK  1208  SYS1.PAGELOC1
> LOCAL     51%   OK  1308  SYS1.PAGELOC2
> LOCAL     32%   OK  1308  SYS1.PAGELOC3
> LOCAL     53%   OK  1207  SYS1.PAGELOC4
> LOCAL     37%   OK  1207  SYS1.PAGELOC5
> LOCAL     53%   OK  1218  SYS1.PAGELOC6
> LOCAL     35%   OK  1218  SYS1.PAGELOC7

> I can remember (but not pinpoint) when usage stayed 
> very low all week long.

Two things come to my mind on this: 

I have only ever seen wildly different numbers like yours in page data set 
percentage usage (when they are all the same size) when page data sets were 
added later, when the rest already had a certain usage. It seemed that adding a 
page ds doesn't favour that page ds so it reaches the same threshold as the 
others, but instead it gets pages in round-robin fashion, slowly building up 
percentage usage, but never reaching the usage of the previous page ds's. In 
our case, all page ds were the same size, too, and were all behind the same 
controller. It took an IPL to even out usage.

Do you have that CHECK(IBMASM,ASM_LOCAL_SLOT_USAGE) health check active on that 
system? I once used the exception thrown via the hardcopy log messages to 
pinpoint that usage increased way before I thought it had increased. It was a 
gradual creep.

I had also seen similar (in my opinion strange) behaviour, and in essence I 
established a reporting network for storage usage, including total amount of 
slots and paging rates. By now, that is quite a trend grafic. Some of the 
behaviour visible in those grafics was also quite unexpected. Mostly, I used 
the numbers to get those lpars a bit more real storage when we migrated to 1.12 
and had several RSM problems that never were found. They went away with just a 
bit more real storage. But I had to fight tooth and nail for it. One would 
think that that real storage was intended for my personal enjoyment, the way my 
management kept withholding it for z/OS while throwing it at z/Linux....

Barbara

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