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Operating System - OpenVMS
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Memory/Buffer memory clear in OpenVMS

Sumant M Kumar
Frequent Advisor

Memory/Buffer memory clear in OpenVMS

Dear Experts,


Is there any command in OpenVMS to clear memory/buffer memory for better system performance. We can do memory clear in RHEL but how we can do in OpenVMS? Please suggest




SK Mishra

Steven Schweda
Honored Contributor

Re: Memory/Buffer memory clear in OpenVMS

Hein van den Heuvel
Honored Contributor

Re: Memory/Buffer memory clear in OpenVMS

I recommend putting more air in the tires as a first step.


SET CACHE/RESET on it's own only clears the counters. Nothing else.


Check out: mcr sysgen HELP SYS_PARAM VCC_MAX_CACHE


Anyway.. what makes you think you can make the system better by flushing a cache?


Just because your Linux implementation is apparently broken, does not mean OpenVMS woudl be suffering form the same ailement does it?


What are the reasons you think there may or might not be a problem in this space?

Are there any problem indicators at all? Resource usage? CPU/IO/Memory? Pagefaulting?


Finally... when I think I need to decrease my system performance and want to make the cache do a worse job, then I just allocate a humongous RAM drive to steal the pages.



$ INIT MDA0:/size=12345678  RAM ! (6GB)


$ INIT MDA0:/size=0 ! And give it all back


Good luck!



Meten is Weten.

Niet weten is zweten.






John Gillings
Honored Contributor

Re: Memory/Buffer memory clear in OpenVMS

I'm curious, what performance is improved by clearing memory?


By "clearing" do you mean filling them with zeros? What is the mechanism by which system performance is improved?


Do you have a performance problem that you're trying to fix? If so, what are the symptoms?

A crucible of informative mistakes
Valued Contributor

Re: Memory/Buffer memory clear in OpenVMS

Easy... @sys$system:shutdown.


Sure, it's abrupt but it fulfils your vague question...