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7 replies Latest Post - ‏2012-02-23T05:08:02Z by SystemAdmin
aix91246
aix91246
17 Posts
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Pinned topic missing memory???

‏2012-02-21T19:31:06Z |
My 9117-MMB partition that is defined with 32gb of memory, only shows up with 31.8gb.

topas shows: Real,MB 32512

svmon -O,unit=GB shows: memory 31.8

Wondering if anyone has seen anything similar. I've got a PMR open with IBM with not much progress to date.
Updated on 2012-02-23T05:08:02Z at 2012-02-23T05:08:02Z by SystemAdmin
  • SystemAdmin
    SystemAdmin
    2402 Posts
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    Re: missing memory???

    ‏2012-02-22T09:44:52Z  in response to aix91246
    Am sure be watching the right value in svmon (ROW=memory, COLUMN=size)

    I can match the memory value from nmon and svmon for my system (verified with bootinfo -r) .
    Please share the same output from your machine
    #cat hostame_120210_1651.nmon | grep -i realmem
    BBBP,442,lsattr -El sys0,"realmem 2097152 Amount of usable physical memory in Kbytes False"
    1. svmon -O,unit=GB
    Unit: GB

    size inuse free pin virtual available mmode
    memory 2.00 1.96 0.04 0.56 1.15 0.74 Ded
    pg space 0.50 0

    work pers clnt other
    pin 0.49 0 0 0.07
    in use 1.15 0 0.81
    #
    1. bootinfo -r
    2097152
    #
    1. bc
    2097152/1024
    2048
    2048/1024
    2
    quit
    • aix91246
      aix91246
      17 Posts
      ACCEPTED ANSWER

      Re: missing memory???

      ‏2012-02-22T13:27:41Z  in response to SystemAdmin
      sorry to not be perfectly clear. this is a system with 16gb x 2.0 ame.

      BBBP,674,lsattr -El sys0,"realmem 16777216 Amount of usable physical memory in Kbytes False"

      bootinfo -r
      16777216

      topas:
      AME
      TMEM,MB 16383

      svmon -O,unit=GB
      Unit: GB

      size inuse free pin virtual available mmode
      memory 31.8 20.8 11.0 5.15 20.3 10.9 Ded-E
      • SystemAdmin
        SystemAdmin
        2402 Posts
        ACCEPTED ANSWER

        Re: missing memory???

        ‏2012-02-22T14:12:48Z  in response to aix91246
        $ bc
        16777216/1024
        16384
        16384/1024
        16

        You should be a happy man, having only 16GB physical memory assigned to this partition you are still able to see 31+GB of memory !
        ALL CREDIT GOES TO ACTIVE MEMORY EXPANSION :-) making you enable to pump twice the physical installed memory.

        Since this is an MMB server, i don't think it would come with 16GB * 2 memory only, if at all this is the case please check the other partitions hosted on the same box. they would be the owner for rest of the memory in your server.

        let me know if it helps.
        • aix91246
          aix91246
          17 Posts
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          Re: missing memory???

          ‏2012-02-22T14:19:58Z  in response to SystemAdmin
          No, it does not help. Every other partition with 16gb x 2.0ame have 32.0gb. This one machine has 31.8gb. This is an anomoly, most likely either in libperfstat or machine firmware, that needs to be resolved.
          • SystemAdmin
            SystemAdmin
            2402 Posts
            ACCEPTED ANSWER

            Re: missing memory???

            ‏2012-02-22T14:32:21Z  in response to aix91246
            Got your point of worry.

            Some Qs,
            -Are all the partitions running same type of workload ?
            -Are you able to see higher paging in this partition ?
            -Are you using same OS-Verion-TL-SP on all the partitions ?
            Some time it is the workload that don't work as you expect and you may notice a memory deficit with AME.

            When configuring the memory expansion factor for an LPAR, it is possible that a memory expansion factor might be chosen that is too large and cannot be achieved based on the compressibility of the workload. When the memory expansion factor for an LPAR is too large, then a memory expansion deficit forms, indicating that the LPAR cannot achieve its memory expansion factor target.

            The effect of a memory deficit is the same as the effect of configuring an LPAR with too little memory. When a memory deficit occurs, the operating system cannot achieve the expanded memory target configured for the LPAR, and the operating system might have to resort to paging out virtual memory pages to paging space
            Find an example of the sample output showing deficit memory,

            AME Statistics: Average Min Max




            AME CPU Usage (Phy. Proc Units) 0.25 6% 0.01 0% 0.50 13%
            Compressed Memory (MB) 264 13% 264 13% 264 13%
            Compression Ratio 2.15 2.15 2.16
            Deficit Memory Size (MB) 562 55% 562 55% 562 55%

            This section of the report shows the AME CPU Usage, Compressed Memory, Compression Ratio & Deficit Memory. In achieving the expanded memory size.
            Otherwise the tool will not report this information. For example in the above report, it can be observed that there is an average memory deficit of 562 MB which is 55% of the Target Expanded Memory Size of 2 GB (which is reported in the System Configuration Section when AME is enabled).
            The report also shows on an average 264 MB out of 2GB of expanded memory is in compressed form as reported against Compressed Memory.
            To eliminate a memory deficit, the LPAR's memory expansion factor should be reduced. However, reducing the memory expansion factor reduces the LPAR's expanded memory size. Thus to keep the LPAR's expanded memory size the same, the memory expansion factor must be reduced and more memory must be added to the LPAR. Both the LPAR's memory size and memory expansion factor can be changed dynamically.
            • aix91246
              aix91246
              17 Posts
              ACCEPTED ANSWER

              Re: missing memory???

              ‏2012-02-22T16:37:40Z  in response to SystemAdmin
              there is no deficit and there is no paging. the OS levels are all the same.
              • SystemAdmin
                SystemAdmin
                2402 Posts
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                Re: missing memory???

                ‏2012-02-23T05:08:02Z  in response to aix91246
                Please share the amepat output.
                have you made any progress on the PMR opened for this ? please do share the findings.