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IT00391: MON_GET_MEMORY_SET DISPLAYS WRONG MEMORY SET STATISTIC FOR MEMORY_SET_SIZE

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APAR status

  • Closed as program error.

Error description

  • MON_GET_MEMORY_SET is not displaying the correct memory set
    statistic for "MEMORY_SET_SIZE".  It is intended to represent a
    point-in-time maximum memory commitment limit (as controlled by
    the instance_memory governance).  Instead it represents an
    internal virtual memory accounting amount, and in many cases
    will significantly overstate the "maximum memory commitment
    limit" (also known as instance memory usage/reservation)
    
    As an example, after increasing and decreasing the database
    memory configuration for the SAMPLE database, we have correct
    values shown through the db2pd -dbptnmem and -memsets tools, but
    MON_GET_MEMORY_SET overstates the memory set size/limit.
    
    db2pd -dbptnmem:
    Name             Mem Used (KB) HWM Used (KB) Cached (KB)
    ========================================================
    ...
    DB-SAMPLE               145152       1137152       24064
    
    The 145152 KB amount is the correct size / instance memory used
    statistic.
    
    db2pd -db sample -memsets :
    Memory Sets:
    Name         Address            Id          Size(Kb)   ...
    SAMPLE       0x0700000050000000 711983157   145216 ...
    
    Size is 145216 KB (a slight difference due to metadata).
    
    MON_GET_MEMORY_SET:
    db2 select MEMORY_SET_TYPE,MEMORY_SET_SIZE from
    table"(mon_get_memory_set('DATABASE',null,null))"
    
    MEMORY_SET_TYPE                  MEMORY_SET_SIZE
    -------------------------------- --------------------
    DATABASE                                      1105068
    
    1105068 KB is the overstated amount.
    

Local fix

  • Use the "-memsets" option of the db2pd command to determine the
    correct memory set size
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * All systems are affected                                     *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Use workaround - see Local Fix                               *
    ****************************************************************
    

Problem conclusion

  • Problem first fixed in DB2 Version 9.7 Fix Pack 10
    

Temporary fix

  • see Local Fix
    

Comments

APAR Information

  • APAR number

    IT00391

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    970

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2014-03-18

  • Closed date

    2014-11-24

  • Last modified date

    2014-11-24

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

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

    IT02443 IT02448

Modules/Macros

  • sqo
    

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • R970 PSN

       UP

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Document Information

Modified date:
24 November 2014