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  • 1.  AIX VMM configuration for paging space

    Posted Wed September 30, 2009 09:34 AM

    Originally posted by: SystemAdmin


    I have an application which uses 64GB memory. The AIX 61 machine has 200GB memory but only a small paging space. When my application runs, I observed large paging space usage percentage (>90%) although there is still lots of free memory available. I am wondering how to configure the VMM to use less paging space when there is free memory available. Thanks.
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  • 2.  Re: AIX VMM configuration for paging space

    Posted Wed October 07, 2009 12:45 PM

    Originally posted by: flodstrom


    I think even larger systems such as your machine do use some page space even if there's plenty of physical memory available. It has to do with how virtual memory works.

    I could be wrong, but I don't think there are any direct ways of tuning AIX6.1 to change page space priority? That said I would not recommend changing page space behaviour (if possible), I would leave the system to decide about this.

    Just for curiosity, what is the size of your page space? To me it sounds like you perhaps should consider increasing it if it's always at +90% used?
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  • 3.  Re: AIX VMM configuration for paging space

    Posted Tue October 13, 2009 02:55 PM

    Originally posted by: tips_luo


    I am not sure but I found the lsps -a command displays the maximum paging space that has ever been used, rather than the current used paging space.
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  • 4.  Re: AIX VMM configuration for paging space

    Posted Wed October 14, 2009 12:28 AM

    Originally posted by: SystemAdmin


    tips_luo: I do not think thats the way it works. We have had memory hogging applications and when they are stopped, we see that paging space utilization also reduces (as seen in lsps -a). So it could be that applications can designed to request reservation in paging space (not referring to "early allocation policy") and that leads to higher utilization than what actually is.

    r/
    R
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  • 5.  Re: AIX VMM configuration for paging space

    Posted Wed October 14, 2009 05:09 AM

    Originally posted by: tony.evans


    How much paging space do you have configured? What is small? 512M? 5G?
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  • 6.  Re: AIX VMM configuration for paging space

    Posted Wed October 14, 2009 09:15 AM

    Originally posted by: Holgervk


    Paging-space that a process uses or used is not freed until the process exits.
    AIX does not use (much) paging-space when there is free memory. Thus, at the moment when AIX used the paging-space, there was not enough free memory. Maybe due to high usage of filecache (backups..).
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