IBM Support

IT29399: SLOW CONNECTION DUE TO CONFLICT ON SQLDBCONF (DATABASE CONFIGURATION FILE).

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APAR status

  • Closed as program error.

Error description

  • Frequent updates to config parameters may cause db2agent to hit
    file sharing violation.
    Such a parameter could be MAXAPPLS on the automatic setting that
    is incremented when the limit is exceeded.
    db2agent is the agent servicing connection request and trying to
    increase max application.
    
    A sharing violation is encountered when updating the DB config
    file, then the config update will be delayed by at least 10
    seconds.
    
    Following entry will show up in db2diag.log:
    ----------------
    2019-03-31-21.49.44.270148-240 I29995A676           LEVEL:
    Warning
    PID     : 20775166             TID : 77619          PROC :
    db2sysc 0
    INSTANCE: db2inst1             NODE : 000           DB   :
    SAMPLE
    APPHDL  : 0-250                APPID:
    127.0.0.1.64210.190401014926
    AUTHID  : TESTER               HOSTNAME: testaix
    EDUID   : 96675                EDUNAME: db2agent (SAMPLE) 3
    FUNCTION: DB2 UDB, config/install, sqlf_openfile, probe:3072
    MESSAGE : File not found error was incorrectly detected as file
    successfully
              opened after multiple attempts.
    DATA #1 : String, 62 bytes
    /home/db2inst1/db2inst1/NODE0000/SQL00001/SQLDBCONF
    DATA #2 : signed integer, 4 bytes
    ---------------
    
    Conflicts in SQLDBCONF can occur in the following environments:
    - STMM is enabled and automatic DB config parameters that are
    tuned by it
    - low starting MAXAPPLS automatic value with large number of
    concurrent connections
    - Concurrent read / write operations on the DB config (e.g. GET
    DB CFG and UPDATE DB CFG)
    
    For example, one scenario that leads to this problem is when
    MAXAPPLS in database configuration is set to a very small
    number, while being AUTOMATIC.
    Each database connection tries to increase MAXAPPLS, resulting
    in file sharing violation in SQLDBCONF.
    The external symptom is the noticeable slowdown in database
    connections by at least 10 seconds.
    The db2diag.log will show a rapid series of messages, each
    trying to update MAXAPPLS, as shown below:
    
    2019-03-06-09.07.45.827897 I40970A536 LEVEL: Event
    <snipped...>
    EDUID : 1234 EDUNAME: db2agent (SAMPLE) 3
    FUNCTION: DB2 UDB, config/install, sqlfLogUpdateCfgParam,
    probe:20
    CHANGE : CFG DB WPROPDB2: "Maxappls" From: "126" <automatic> To:
    "175" <automatic>
    
    2019-03-06-09.07.45.854713 I41507A536 LEVEL: Event
    <snipped...>
    EDUID : 5678 EDUNAME: db2agent (SAMPLE) 3
    FUNCTION: DB2 UDB, config/install, sqlfLogUpdateCfgParam,
    probe:20
    CHANGE : CFG DB WPROPDB2: "Maxappls" From: "175" <automatic> To:
    "177" <automatic>
    
    2019-03-06-09.07.45.862132 I42044A536 LEVEL: Event
    <snipped...>
    EDUID : 9012 EDUNAME: db2agent (SAMPLE) 3
    FUNCTION: DB2 UDB, config/install, sqlfLogUpdateCfgParam,
    probe:20
    CHANGE : CFG DB WPROPDB2: "Maxappls" From: "177" <automatic> To:
    "178" <automatic>
    
    Note:
    The first db2diag.log message shown in description incorrectly
    indicates "file not found", but the error actually detected is
    "file sharing violation" in this case.
    Conflicts can occur on either Global or each member SQLDBCONF on
    purescale environment.
    

Local fix

  • Avoid a situation where database configuration needs to be
    updated too frequently.
    Set MAXAPPLS to a fixed large number(e.g. 1000).
    For example
    db2 update db cfg for sample using MAXAPPLS 1000
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * all                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to Db2 11.1.4.6 or higher                            *
    ****************************************************************
    

Problem conclusion

  • Upgrade to Db2 11.1.4.6 or higher
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT29399

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    B10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2019-06-11

  • Closed date

    2021-03-31

  • Last modified date

    2021-03-31

  • 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

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

[{"Line of Business":{"code":"LOB10","label":"Data and AI"},"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSEPGG","label":"Db2 for Linux, UNIX and Windows"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"11.1"}]

Document Information

Modified date:
01 April 2021