what's up with pinned pages & external pager filesystem - Aix

This is a discussion on what's up with pinned pages & external pager filesystem - Aix ; Original problem: Can not fork ... not enough resources - and box face plants Looking through nmon stats from before the crash the virtual memory sloooowly is used up till above happens. I've poured through all the stats and the ...

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Thread: what's up with pinned pages & external pager filesystem

  1. what's up with pinned pages & external pager filesystem

    Original problem: Can not fork ... not enough resources - and box
    face plants

    Looking through nmon stats from before the crash the virtual memory
    sloooowly is used up till above happens.

    I've poured through all the stats and the "trend" I am fixated on
    now ...

    12/20/07-21:27:06==== 429904 pinned pages
    12/20/07-21:27:06==== 749500 external pager filesystem I/
    Os blocked with no fsbuf

    12/20/07-22:27:06==== 431187 pinned pages
    12/20/07-22:27:06==== 749514 external pager filesystem I/
    Os blocked with no fsbuf

    12/20/07-23:27:06==== 431768 pinned pages
    12/20/07-23:27:06==== 749545 external pager filesystem I/
    Os blocked with no fsbuf

    12/21/07-00:27:06==== 432210 pinned pages
    12/21/07-00:27:06==== 749574 external pager filesystem I/
    Os blocked with no fsbuf

    12/21/07-01:27:06==== 433832 pinned pages
    12/21/07-01:27:06==== 749626 external pager filesystem I/
    Os blocked with no fsbuf

    12/21/07-02:27:06==== 434108 pinned pages
    12/21/07-02:27:06==== 749687 external pager filesystem I/
    Os blocked with no fsbuf

    12/21/07-03:27:06==== 434649 pinned pages
    12/21/07-03:27:06==== 857633 external pager filesystem I/
    Os blocked with no fsbuf

    12/21/07-04:27:06==== 435089 pinned pages
    12/21/07-04:27:06==== 857678 external pager filesystem I/
    Os blocked with no fsbuf

    12/21/07-05:27:06==== 435615 pinned pages
    12/21/07-05:27:06==== 857717 external pager filesystem I/
    Os blocked with no fsbuf

    There iare no other obvious "problems" .. but I can see the virtual
    memory disappearing again ... and I'm 99% sure we will face plant
    eventually again.

    The increase in pinned pages seems to be related to a huge humongous
    tar that happens early morning. Everyday that happens the pinned pages
    jump a smidgen ... never to come down again ... but I can find no more
    info ... let alone how to fix it ...

    There are some tuning things I could potentially do - but I'm not just
    randomly going to change things hoping it does something ... I want to
    learn something ... ie KNOW what fixed it ....

  2. Re: what's up with pinned pages & external pager filesystem

    "external pager filesystem I/Os blocked with no fsbuf" refers to the
    number of external pager client filesystem I/O requests blocked
    because no fsbuf was available. JFS2 is an external pager client
    filesystem. If this grows as in your case you can typically set
    j2_nBufferPerPagerDevice to 1024 using ioo and check. The default
    value is 512. The filesystem should be remounted for changed to take
    effect.

    Futher, I have also read in the help pages that ideally
    j2_dynamicBufferPreallocation should be tuned first and this value can
    be increased and if still you find the value of "external pager
    filesystem I/Os blocked with no fsbuf" increasing, tune
    j2_nBufferPerPagerDevice. This is because initially buffers are
    alocated as per j2_nBufferPerPagerDevice and buffers are allocated and
    destroyed dynamic past this value.

    Also check for other buffer sizes too like pv_min_pbufs, munfsbufs
    etc.
    HTH
    -Ashok

    ad...@yahoo.com wrote:
    > Original problem: Can not fork ... not enough resources - and box
    > face plants
    >
    > Looking through nmon stats from before the crash the virtual memory
    > sloooowly is used up till above happens.
    >
    > I've poured through all the stats and the "trend" I am fixated on
    > now ...
    >
    > 12/20/07-21:27:06==== 429904 pinned pages
    > 12/20/07-21:27:06==== 749500 external pager filesystem I/
    > Os blocked with no fsbuf
    >
    > 12/20/07-22:27:06==== 431187 pinned pages
    > 12/20/07-22:27:06==== 749514 external pager filesystem I/
    > Os blocked with no fsbuf
    >
    > 12/20/07-23:27:06==== 431768 pinned pages
    > 12/20/07-23:27:06==== 749545 external pager filesystem I/
    > Os blocked with no fsbuf
    >
    > 12/21/07-00:27:06==== 432210 pinned pages
    > 12/21/07-00:27:06==== 749574 external pager filesystem I/
    > Os blocked with no fsbuf
    >
    > 12/21/07-01:27:06==== 433832 pinned pages
    > 12/21/07-01:27:06==== 749626 external pager filesystem I/
    > Os blocked with no fsbuf
    >
    > 12/21/07-02:27:06==== 434108 pinned pages
    > 12/21/07-02:27:06==== 749687 external pager filesystem I/
    > Os blocked with no fsbuf
    >
    > 12/21/07-03:27:06==== 434649 pinned pages
    > 12/21/07-03:27:06==== 857633 external pager filesystem I/
    > Os blocked with no fsbuf
    >
    > 12/21/07-04:27:06==== 435089 pinned pages
    > 12/21/07-04:27:06==== 857678 external pager filesystem I/
    > Os blocked with no fsbuf
    >
    > 12/21/07-05:27:06==== 435615 pinned pages
    > 12/21/07-05:27:06==== 857717 external pager filesystem I/
    > Os blocked with no fsbuf
    >
    > There iare no other obvious "problems" .. but I can see the virtual
    > memory disappearing again ... and I'm 99% sure we will face plant
    > eventually again.
    >
    > The increase in pinned pages seems to be related to a huge humongous
    > tar that happens early morning. Everyday that happens the pinned pages
    > jump a smidgen ... never to come down again ... but I can find no more
    > info ... let alone how to fix it ...
    >
    > There are some tuning things I could potentially do - but I'm not just
    > randomly going to change things hoping it does something ... I want to
    > learn something ... ie KNOW what fixed it ....


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