I've been trying to track down what's causing system 1M page demotions on our
test system. The component trace IBM gave me shows, in part:
SYS5 SGTDEM64 00000063 12:44:53.270019 Demote 1M 64 bit page
FUNC1... COPYSRVH High Virtual Copy Service
JOBN1... ZUMCCMG1 ASID1... 0215 PLOCKS.. 8800C001 CPU..... 0006
JOBN2... ZUMCCMG3 ASID2... 022D RLOCKS.. 8800C001 RLOCKDET 0800
KEY..... 0036 ADDR.... 035E1008 ALET.... 00000000
The COPYSRVH function isn't well documented but, from I see, UNIX fork
processing invokes it to copy memory to the new process. This makes sense in
that JOBN1 and JOBN3 are both USS processes.
Both LFAREA and SCM on this system are less than 1% used. Why is z/OS demoting
pages?
Thanks.
Robert Crawford
Mainframe Management
United Services Automobile Association
(210) 913-3822
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