PBUF/PSBUF/FSBUF question - Aix

This is a discussion on PBUF/PSBUF/FSBUF question - Aix ; Hello gurus After reading the man page on vmstat, it still isn't quite clear to me what the pbuf/psbuf/fsbuf buffers mean in the following vmstat -v output: 0 pending disk I/Os blocked with no pbuf 371595 paging space I/Os blocked ...

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  1. PBUF/PSBUF/FSBUF question

    Hello gurus

    After reading the man page on vmstat, it still isn't quite clear to me
    what the pbuf/psbuf/fsbuf buffers mean in the following vmstat -v
    output:
    0 pending disk I/Os blocked with no pbuf
    371595 paging space I/Os blocked with no psbuf
    2178290 filesystem I/Os blocked with no fsbuf

    The man page states
    pending disk I/Os blocked with no pbuf
    Number of pending disk I/O requests blocked because no pbuf was
    available. Pbufs are pinned memory buffers used to hold I/O requests
    at the logical volume manager layer.
    paging space I/Os blocked with no psbuf
    Number of paging space I/O requests blocked because no psbuf was
    available. Psbufs are pinned memory buffers used to hold I/O
    requests at the virtual memory manager layer.
    filesystem I/Os blocked with no fsbuf
    Number of filesystem I/O requests blocked because no fsbuf was
    available. Fsbuf are pinned memory buffers used to hold I/O requests
    in the filesystem layer.

    Could someone give me an example when these counters get incremented?

    Thanks a lot

  2. Re: PBUF/PSBUF/FSBUF question

    On Oct 18, 1:47*pm, Miguel Sanders wrote:
    > Hello gurus
    >
    > After reading the man page on vmstat, it still isn't quite clear to me
    > what the pbuf/psbuf/fsbuf buffers mean in the following vmstat -v
    > output:
    > * * * * * * * * 0 pending disk I/Os blocked with no pbuf
    > * * * * * * * * 371595 paging space I/Os blocked with no psbuf
    > * * * * * * * * 2178290 filesystem I/Os blocked with no fsbuf
    >
    > The man page states
    > * * * * * * * pending disk I/Os blocked with no pbuf
    > Number of pending disk I/O requests blocked because no pbuf was
    > available. Pbufs are pinned memory buffers used to hold I/O requests
    > at the logical volume manager layer.
    > * * * * * * * paging space I/Os blocked with no psbuf
    > Number of paging space I/O requests blocked because no psbuf was
    > available. Psbufs are pinned memory * buffers used to hold I/O
    > requests at the virtual memory manager layer.
    > * * * * * * * filesystem I/Os blocked with no fsbuf
    > Number of filesystem I/O requests blocked because no fsbuf was
    > available. Fsbuf are pinned memory buffers *used to hold I/O requests
    > in the filesystem layer.
    >
    > Could someone give me an example when these counters get incremented?
    >
    > Thanks a lot


    You might want to run vmstat over a period of time and monitor these
    parameters, as due to shortfall of these buffers, I/O are blocked. You
    can modify their settings thru "ioo". Here is the explanations as I
    understand it:

    pbuf: Are buffers defined and used at LVM level. (Use lvmo instead of
    ioo).
    psbuf: Are buffers are for paging space operation
    fsbuf: Are for filesystems ("ioo"/"j2_nBufferPerPagerDevice")

    -Khatir



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