Thank you for posting the output. That helps to confirm the issue. I have edited your post with some of the relevant information.
The reported PV size (PSize) is bigger (420.00G) than the...
If you ask like that - ask Google!
Or provide more information:
Where do you see the error message? Terminal/Console? Syslog file ...? Application ...?
When and how often? Once every full hour?...
It would also be interessting when the paging to PS occurs. I saw that RMAN accumulated used pgsp at nightly backup jobs (over some days/weeks) but on days peak loads had about no paging out at all....
agent.kgb is absolutely correct: paging space is a "plan B", if "plan A" (memory) fails. Your system shouldn't need to use it under normal circumstance and it should be there only for contingency.
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