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IC71508: STMM MIGHT INCORRECTLY CALCULATE DATABASE MEMORY TARGETS SIZE UNDER CERTAIN CIRCUMSTANCES

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APAR status

  • Closed as program error.

Error description

  • STMM incorrectly calculates database memory targets size and an
    overflow happened due to the free memory target being greater
    than database configured memory set when there isn't enough free
    memory in the machine.
    
    STMM tries to leave a certain percentage of memory as free
    memory, called the free memory target. When the free memory
    target is bigger than a database memory set while there isn't
    enough free memory in the machine, STMM may "incorrectly" decide
    to shrink the database memory set below 0. This leads to an
    overflow of the target database memory set size and the target
    consumer size those are reported in STMM.log
    
    Additionally, the error message like "ZRC=0xFFFFEC49=-5047" will
    appear in db2diag.log whenever the free memory in the box runs
    out, The error will also disappear on its own when some free
    memory becomes available in the box.
    
    Here is an example db2diag.log entry :
    
    2010-08-23-01.22.46.494522+480 E47256126A631      LEVEL: Warning
    PID     : 303152               TID  : 35746       PROC : db2sysc
    0
    INSTANCE: DB2INST1             NODE : 000         DB   : SAMPLE
    APPHDL  : 1-60027              APPID: *N1.DB2.100822171046
    AUTHID  : DB2INST1
    EDUID   : 35746                EDUNAME: db2stmm (SAMPLE) 0
    FUNCTION: DB2 UDB, Self tuning memory manager,
    stmmCheckIfFreeMemoryIsEnoughForSizeIncr, probe:667
    MESSAGE : ZRC=0xFFFFEC49=-5047
    DATA #1 : String, 143 bytes
    There is not enough free memory for size increase. Free memory
    in pages: Physical memory = 0, Instance memory = 160917,
    Database memory = 33072
    
    Here is an example stmm.X.log entry:
    
    2010-08-23-01.22.46.493934+480 I8862389A929       LEVEL: Event
    PID     : 303152               TID  : 35746       PROC : db2sysc
    0
    INSTANCE: DB2INST1             NODE : 000         DB   : SAMPLE
    APPHDL  : 1-60027              APPID: *N1.DB2.100822171046
    AUTHID  : DB2INST1
    EDUID   : 35746                EDUNAME: db2stmm (SAMPLE) 0
    FUNCTION: DB2 UDB, Self tuning memory manager,
    stmmGetDBMemDataAutomatic, probe:3824
    DATA #1 : String, 489 bytes
    Configured memory on the system: 2621440
    Memory currently available on the system: 147239
    Configured memory on the partition: 1102245
    Memory currently available on the partition: 160917
    Set's configured size: 199968
    Overflow left: 33072
    Uncommited size: 86256
    Target consumer size: 4500081190153110
    Current consumer size: 166896
    Max growth: 0
    Current overflow percent: 0.200000
    Target overflow percent: 0.000781
    Average benefit: 0
    Global benefit: Instance: DB2INST1 DB: SAMPLE     Benefit: 0
    
    2010-08-23-01.22.46.494730+480 I8863319A631       LEVEL: Warning
    PID     : 303152               TID  : 35746       PROC : db2sysc
    0
    INSTANCE: DB2INST1             NODE : 000         DB   : SAMPLE
    APPHDL  : 1-60027              APPID: *N1.DB2.100822171046
    AUTHID  : DB2INST1
    EDUID   : 35746                EDUNAME: db2stmm (SAMPLE) 0
    FUNCTION: DB2 UDB, Self tuning memory manager,
    stmmCheckIfFreeMemoryIsEnoughForSizeIncr, probe:667
    MESSAGE : ZRC=0xFFFFEC49=-5047
    DATA #1 : String, 143 bytes
    There is not enough free memory for size increase. Free memory
    in pages: Physical memory = 0, Instance memory = 160917,
    Database memory = 33072
    
    2010-08-23-01.22.46.529929+480 I8863951A627       LEVEL: Error
    PID     : 303152               TID  : 35746       PROC : db2sysc
    0
    INSTANCE: DB2INST1             NODE : 000         DB   : SAMPLE
    APPHDL  : 1-60027              APPID: *N1.DB2.100822171046
    AUTHID  : DB2INST1
    EDUID   : 35746                EDUNAME: db2stmm (SAMPLE) 0
    FUNCTION: DB2 UDB, Self tuning memory manager,
    stmmUpdateDBConfig, probe:275
    MESSAGE : ZRC=0x82AE00A7=-2102525785=STMM_CONFIG_UPDATE_FAILED
              "An attempted configuration update failed"
    DATA #1 : String, 79 bytes
    Error updating parameter Database_memory, updateValue = 208620,
    sqlcode = -5047
    
    2010-08-23-01.22.46.530322+480 I8864579A664       LEVEL: Event
    PID     : 303152               TID  : 35746       PROC : db2sysc
    0
    INSTANCE: DB2INST1             NODE : 000         DB   : SAMPLE
    APPHDL  : 1-60027              APPID: *N1.DB2.100822171046
    AUTHID  : DB2INST1
    EDUID   : 35746                EDUNAME: db2stmm (SAMPLE) 0
    FUNCTION: DB2 UDB, Self tuning memory manager,
    stmmMaintainOverflowSize, probe:4403
    DATA #1 : String, 225 bytes
    Original overflow size: 33072
    Target DBMem size: 4503599627361988
    Growth limit: 68719276752
    Expected DBMem size: 208620
    Current DBMem size: 199968
    Current consumer size: 166896
    Overflow size: 39993
    Overflow percent: 0.200000
    
    If you could see that unrealistically big figures for 'Target
    DBMem size' and 'Target consumer size' are appeared in
    STMM.x.log, in the example above, they are '4503599627361988'
    and '4500081190153110' respectively, then it is an indication
    that this problem applies to your environment.
    

Local fix

  • N/A
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * ALL                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * STMM incorrectly calculates database memory targets size and *
    * an overflow happened due to the free memory target being     *
    * greater than database configured memory set when there isn't *
    * enough free memory in the machine.                           *
    *                                                              *
    *                                                              *
    * STMM tries to leave a certain percentage of memory as free   *
    * memory, called the free memory target. When the free memory  *
    * target is bigger than a database memory set while there      *
    * isn't enough free memory in the machine, STMM may            *
    * "incorrectly" decide to shrink the database memory set below *
    * 0. This leads to an overflow of the target database memory   *
    * set size and the target consumer size those are reported in  *
    * STMM.log                                                     *
    *                                                              *
    *                                                              *
    * Additionally, the error message like "ZRC=0xFFFFEC49=-5047"  *
    * will appear in db2diag.log whenever the free memory in the   *
    * box runs                                                     *
    * out, The error will also disappear on its own when some free *
    * memory becomes available in the box.                         *
    *                                                              *
    *                                                              *
    *                                                              *
    * Here is an example db2diag.log entry :                       *
    *                                                              *
    *                                                              *
    *                                                              *
    * 2010-08-23-01.22.46.494522+480 E47256126A631      LEVEL:     *
    * Warning                                                      *
    * PID    : 303152              TID  : 35746      PROC :        *
    * db2sysc                                                      *
    * 0                                                            *
    *                                                              *
    * INSTANCE: DB2INST1            NODE : 000        DB  : SAMPLE *
    * APPHDL  : 1-60027              APPID: *N1.DB2.100822171046   *
    *                                                              *
    * AUTHID  : DB2INST1                                           *
    *                                                              *
    * EDUID  : 35746                EDUNAME: db2stmm (SAMPLE) 0    *
    *                                                              *
    * FUNCTION: DB2 UDB, Self tuning memory manager,               *
    *                                                              *
    * stmmCheckIfFreeMemoryIsEnoughForSizeIncr, probe:667          *
    *                                                              *
    * MESSAGE : ZRC=0xFFFFEC49=-5047                               *
    *                                                              *
    * DATA #1 : String, 143 bytes                                  *
    *                                                              *
    * There is not enough free memory for size increase. Free      *
    * memory                                                       *
    * in pages: Physical memory = 0, Instance memory = 160917,     *
    *                                                              *
    * Database memory = 33072                                      *
    *                                                              *
    *                                                              *
    *                                                              *
    * Here is an example stmm.X.log entry:                         *
    *                                                              *
    *                                                              *
    *                                                              *
    * 2010-08-23-01.22.46.493934+480 I8862389A929      LEVEL:      *
    * Event                                                        *
    * PID    : 303152              TID  : 35746      PROC :        *
    * db2sysc                                                      *
    * 0                                                            *
    *                                                              *
    * INSTANCE: DB2INST1            NODE : 000        DB  : SAMPLE *
    * APPHDL  : 1-60027              APPID: *N1.DB2.100822171046   *
    *                                                              *
    * AUTHID  : DB2INST1                                           *
    *                                                              *
    * EDUID  : 35746                EDUNAME: db2stmm (SAMPLE) 0    *
    *                                                              *
    * FUNCTION: DB2 UDB, Self tuning memory manager,               *
    *                                                              *
    * stmmGetDBMemDataAutomatic, probe:3824                        *
    *                                                              *
    * DATA #1 : String, 489 bytes                                  *
    *                                                              *
    * Configured memory on the system: 2621440                     *
    *                                                              *
    * Memory currently available on the system: 147239             *
    *                                                              *
    * Configured memory on the partition: 1102245                  *
    *                                                              *
    * Memory currently available on the partition: 160917          *
    *                                                              *
    * Set's configured size: 199968                                *
    *                                                              *
    * Overflow left: 33072                                         *
    *                                                              *
    * Uncommited size: 86256                                       *
    *                                                              *
    * Target consumer size: 4500081190153110                       *
    *                                                              *
    * Current consumer size: 166896                                *
    *                                                              *
    * Max growth: 0                                                *
    *                                                              *
    * Current overflow percent: 0.200000                           *
    *                                                              *
    * Target overflow percent: 0.000781                            *
    *                                                              *
    * Average benefit: 0                                           *
    *                                                              *
    * Global benefit: Instance: DB2INST1 DB: SAMPLE    Benefit: 0  *
    *                                                              *
    *                                                              *
    *                                                              *
    * 2010-08-23-01.22.46.494730+480 I8863319A631      LEVEL:      *
    * Warning                                                      *
    * PID    : 303152              TID  : 35746      PROC :        *
    * db2sysc                                                      *
    * 0                                                            *
    *                                                              *
    * INSTANCE: DB2INST1            NODE : 000        DB  : SAMPLE *
    * APPHDL  : 1-60027              APPID: *N1.DB2.100822171046   *
    *                                                              *
    * AUTHID  : DB2INST1                                           *
    *                                                              *
    * EDUID  : 35746                EDUNAME: db2stmm (SAMPLE) 0    *
    *                                                              *
    * FUNCTION: DB2 UDB, Self tuning memory manager,               *
    *                                                              *
    * stmmCheckIfFreeMemoryIsEnoughForSizeIncr, probe:667          *
    *                                                              *
    * MESSAGE : ZRC=0xFFFFEC49=-5047                               *
    *                                                              *
    * DATA #1 : String, 143 bytes                                  *
    *                                                              *
    * There is not enough free memory for size increase. Free      *
    * memory                                                       *
    * in pages: Physical memory = 0, Instance memory = 160917,     *
    *                                                              *
    * Database memory = 33072                                      *
    *                                                              *
    *                                                              *
    *                                                              *
    * 2010-08-23-01.22.46.529929+480 I8863951A627      LEVEL:      *
    * Error                                                        *
    * PID    : 303152              TID  : 35746      PROC :        *
    * db2sysc                                                      *
    * 0                                                            *
    *                                                              *
    * INSTANCE: DB2INST1            NODE : 000        DB  : SAMPLE *
    * APPHDL  : 1-60027              APPID: *N1.DB2.100822171046   *
    *                                                              *
    * AUTHID  : DB2INST1                                           *
    *                                                              *
    * EDUID  : 35746                EDUNAME: db2stmm (SAMPLE) 0    *
    *                                                              *
    * FUNCTION: DB2 UDB, Self tuning memory manager,               *
    *                                                              *
    * stmmUpdateDBConfig, probe:275                                *
    *                                                              *
    * MESSAGE :                                                    *
    * ZRC=0x82AE00A7=-2102525785=STMM_CONFIG_UPDATE_FAILED         *
    * "An attempted configuration update failed"                   *
    *                                                              *
    * DATA #1 : String, 79 bytes                                   *
    *                                                              *
    * Error updating parameter Database_memory, updateValue =      *
    * 208620,                                                      *
    * sqlcode = -5047                                              *
    *                                                              *
    *                                                              *
    *                                                              *
    * 2010-08-23-01.22.46.530322+480 I8864579A664      LEVEL:      *
    * Event                                                        *
    * PID    : 303152              TID  : 35746      PROC :        *
    * db2sysc                                                      *
    * 0                                                            *
    *                                                              *
    * INSTANCE: DB2INST1            NODE : 000        DB  : SAMPLE *
    * APPHDL  : 1-60027              APPID: *N1.DB2.100822171046   *
    *                                                              *
    * AUTHID  : DB2INST1                                           *
    *                                                              *
    * EDUID  : 35746                EDUNAME: db2stmm (SAMPLE) 0    *
    *                                                              *
    * FUNCTION: DB2 UDB, Self tuning memory manager,               *
    *                                                              *
    * stmmMaintainOverflowSize, probe:4403                         *
    *                                                              *
    * DATA #1 : String, 225 bytes                                  *
    *                                                              *
    * Original overflow size: 33072                                *
    *                                                              *
    * Target DBMem size: 4503599627361988                          *
    *                                                              *
    * Growth limit: 68719276752                                    *
    *                                                              *
    * Expected DBMem size: 208620                                  *
    *                                                              *
    * Current DBMem size: 199968                                   *
    *                                                              *
    * Current consumer size: 166896                                *
    *                                                              *
    * Overflow size: 39993                                         *
    *                                                              *
    * Overflow percent: 0.200000                                   *
    *                                                              *
    *                                                              *
    *                                                              *
    * If you could see that unrealistically big figures for        *
    * 'Target DBMem size' and 'Target consumer size' are appeared  *
    * in STMM.x.log, in the example above, they are                *
    * '4503599627361988' and '4500081190153110' respectively, then *
    * it is an indication that this problem applies to your        *
    * environment.                                                 *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to v9.5FP8                                           *
    ****************************************************************
    

Problem conclusion

  • An overflow of the target database memory set size and the
    target consumer size would not occur
    

Temporary fix

Comments

APAR Information

  • APAR number

    IC71508

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    950

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2010-09-27

  • Closed date

    2011-03-01

  • Last modified date

    2011-05-02

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

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

    IC74557 IC74558

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • R950 PSN

       UP

  • R970 PSN

       UP

[{"Business Unit":{"code":"BU048","label":"IBM Software"},"Product":{"code":"SSEPGG","label":"DB2 for Linux, UNIX and Windows"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"9.5","Edition":"","Line of Business":{"code":"LOB10","label":"Data and AI"}}]

Document Information

Modified date:
02 May 2011