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IT29822: HADR STANDBY WITH ROS CAN HANG DURING ENDING OF REPLAY ONLY WINDOW

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APAR status

  • Closed as program error.

Error description

  • This can problem can be observed when the HADR standby log
    replay position is not moving, and in db2diag.log there is the
    "Replay only window is active" message without a matching
    "Replay only window is inactive, connections to Active Standby
    are allowed" message.
    
    If stack is collected, one can observe an db2redow thread stuck
    in the function sqlprHADRROSRedoWorkerWaitForTCBRefresh() with a
    stack similar to below:
    
    0x00002ACE8B832625
    _Z25ossDumpStackTraceInternalmR11OSSTrapFileiP7siginfoPvmm +
    0x0385
    0x00002ACE8B83222C ossDumpStackTraceV98 + 0x002c
    0x00002ACE8B82D32D _ZN11OSSTrapFile6dumpExEmiP7siginfoPvm +
    0x00fd
    0x00002ACE85E855CF sqlo_trce + 0x03ef
    0x00002ACE85EDB905 sqloDumpDiagInfoHandler + 0x0105
    address: 0x00002ACE7ECF45E0 ; dladdress: 0x00002ACE7ECE5000 ;
    offset in lib: 0x000000000000F5E0 ;
    0x00002ACE7ECF3E4D __nanosleep + 0x002d
    0x00002ACE8B818D11 ossSleep + 0x0051
    0x00002ACE83A5F9F5 sqlorest + 0x00e5
    0x00002ACE85FDDDD5
    _Z39sqlprHADRROSRedoWorkerWaitForTCBRefreshP8sqeAgentP10SQLPR_PR
    CB + 0x01f5
    0x00002ACE85FE4CCD
    _Z15sqlpPRecProcLogP8sqeAgentP8SQLP_ACBP14sqlpMasterDbcb +
    0x0d7d
    0x00002ACE85FC0AB0 _Z20sqlpParallelRecoveryP8sqeAgentP5sqlca +
    0x06f0
    0x00002ACE851D4FFE _Z26sqleSubCoordProcessRequestP8sqeAgent +
    0x00de
    0x00002ACE82CD7E04 _ZN8sqeAgent6RunEDUEv + 0x0824
    0x00002ACE84279CA4 _ZN9sqzEDUObj9EDUDriverEv + 0x00f4
    0x00002ACE83ACD617 sqloEDUEntry + 0x02f7
    address: 0x00002ACE7ECECE25 ; dladdress: 0x00002ACE7ECE5000 ;
    offset in lib: 0x0000000000007E25 ;
    0x00002ACE8C65E34D clone + 0x006d
    
    This problem is due to an extreme timing scenario where the
    first replay only window is started before all the db2redow
    threads are fully initialized.  Recycling the instance and
    activating the standby database can usually avoid the problem.
    

Local fix

  • Root cause is an extreme timing scenario during start up of HADR
    standby database.  Recycle the standby instance and activate the
    standby database again can usually avoid the problem.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * ALL                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to Db2 11.1 Mod 4 Fixpack 5 or higher                *
    ****************************************************************
    

Problem conclusion

  • First fixed in Db2 11.1 Mod 4 Fixpack 5
    

Temporary fix

  • NA
    

Comments

APAR Information

  • APAR number

    IT29822

  • 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

    2019-07-24

  • Closed date

    2020-01-16

  • Last modified date

    2020-01-16

  • 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

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • RB10 PSN

       UP

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

Document Information

Modified date:
16 January 2020