IBM Support

IT04556: THE OS_MEM_FREE COLUMN FROM SYSMASTER:SYSMACHINEINFO IS MISLEADING ON AIX

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APAR status

  • Closed as program error.

Error description

  • Take for example the following query:
    
    select os_mem_free from sysmaster:sysmachineinfo;
    
    This returns the amount of free memory on the OS in bytes.  We
    appear to get this information from the same function that
    gathers that info for OAT (via the SMI query) and onstat -g osi.
    
    The system call being used appears to be grabbing what is seen
    in svmon -G's "free" column.  (see below)  While this does tend
    to be showing a true value for free memory on the system, it is
    not an accurate representation of the real available free
    memory.  That's because this free value incorporates a lot of
    memory reserved/cached by the OS.  Yet this memory can be
    redistributed to new shared memory segments and process heap
    memory if needed.
    
    > svmon -G
    
                     size             inuse             free
    pin            virtual          mmode
    memory     65404928    65258049           9272929    11308121
    Ded
    pg space    5373952      28131
    
                   work                 pers        clnt
    other
    pin           7337054           0             1123
    1934752
    in use       11308121         0             53949928
    ...
    
    
    A more accurate value for free memory on the system (i.e. memory
    that could be available if needed) would be the (memory->size) -
    (memory->virtual).  Or (memory->size) - (in use->work).
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * AIX users                                                    *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Update to IDS-12.10.xC5                                      *
    ****************************************************************
    

Problem conclusion

  • Problem Fixed In IDS-12.10.xC5
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT04556

  • Reported component name

    INFORMIX SERVER

  • Reported component ID

    5725A3900

  • Reported release

    C10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2014-09-23

  • Closed date

    2015-10-16

  • Last modified date

    2015-10-16

  • APAR is sysrouted FROM one or more of the following:

  • APAR is sysrouted TO one or more of the following:

Fix information

  • Fixed component name

    INFORMIX SERVER

  • Fixed component ID

    5725A3900

Applicable component levels

  • RB70 PSN

       UP

  • RB70 PSY

       UP

  • RC10 PSN

       UP

  • RC10 PSY

       UP

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Document Information

Modified date:
16 October 2015