Informix

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  • 1.  ReadAhead for rollback error message

    Posted 11 days ago
    Hello All,
    My customer's Informix encountered a type of error message that didn't normally occur. What could be the cause?


    08/05/22 17:04:27 Logical Log 996906 Complete, timestamp: 0x530fc895.
    08/05/22 17:04:31 Performance Advisory: ReadAhead for rollback failed to find valid LLog page - LSN 996907:6223d8.
    08/05/22 17:04:31 Results: ReadAhead for Rollback has been turned off for this transaction.
    08/05/22 17:05:31 Performance Advisory: ReadAhead for rollback failed to find valid LLog page - LSN 996907:4cc6590.
    08/05/22 17:05:31 Results: ReadAhead for Rollback has been turned off for this transaction.
    08/05/22 17:05:42 Encountered problem processing update on secondary : Cannot read row tn:topas.tnmq_fsts
    08/05/22 17:05:42 partnum:rowid 27263481:0x8a104 SQL:0 ISAM:110
    08/05/22 17:06:45 Logical Log 996907 Complete, timestamp: 0x53193ea5.
    08/05/22 17:06:47 Performance Advisory: ReadAhead for rollback failed to find valid LLog page - LSN 996908:ad6e2c.
    08/05/22 17:06:47 Results: ReadAhead for Rollback has been turned off for this transaction.
    08/05/22 17:06:57 Performance Advisory: ReadAhead for rollback failed to find valid LLog page - LSN 996908:215dbdc.
    08/05/22 17:06:57 Results: ReadAhead for Rollback has been turned off for this transaction.
    08/05/22 17:07:23 Checkpoint Completed: duration was 3 seconds.
    08/05/22 17:07:23 Fri Aug 5 - loguniq 996908, logpos 0x3cb4060, timestamp: 0x531c171f Interval: 501647

    ------------------------------
    SangGyu Jeong
    Software Engineer
    Infrasoft
    Seoul Korea, Republic of
    ------------------------------


  • 2.  RE: ReadAhead for rollback error message

    IBM Champion
    Posted 9 days ago
    Open a PMR Case and report it. New to me. Worst case they tell you "No problem".

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    Art S. Kagel, President and Principal Consultant
    ASK Database Management Corp.
    www.askdbmgt.com
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  • 3.  RE: ReadAhead for rollback error message

    Posted 8 days ago
    The PMR cannot be opened because the customer does not have a renewal contract.

    The same message keeps appearing repeatedly, and after changing the AUTO_READAHEAD parameter value from 1 to 0, it has not occurred.
    Changing that parameter is just my guess.

    ------------------------------
    SangGyu Jeong
    Software Engineer
    Infrasoft
    Seoul Korea, Republic of
    ------------------------------



  • 4.  RE: ReadAhead for rollback error message

    Posted 7 days ago
    Hi SangGyu.

    What IDS version is this? We see the same at two unrelated sites both running 12.10.FC10 on Linux. As that's very specific, I expect upgrading would fix it. We have always ignored it as its only a Performance Advisory, doesn't seem to cause any real problem, and the affected instances are dev/test. I am away this week, but could open a case when I'm back if that would help.

    ------------------------------
    Doug Lawry
    Oninit Consulting
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  • 5.  RE: ReadAhead for rollback error message

    Posted 6 days ago
    Edited by SangGyu Jeong 6 days ago
    Hi Doug,

    Thank you for your interest. That site uses version 12.10.FC14 on AIX.
    As you said, I think the message is close to informational.
    As a result of looking at it for a few days, frequent update operations often rollback due to lock timeout, which is probably the cause.
    It's annoying because the messages happen so often, so I'm going to leave AUTO_READAHEAD off.
    I also advised to increase the lock timeout setting value a bit.

    ------------------------------
    SangGyu Jeong
    Software Engineer
    Infrasoft
    Seoul Korea, Republic of
    ------------------------------



  • 6.  RE: ReadAhead for rollback error message

    Posted 5 days ago
    12.10.xC15 fix list has this APAR : IT32196 Rollback of transactions involving log records > 10k triggers readahead messages in MSGPATH file

    https://www.ibm.com/support/pages/apar/IT32196


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    CASEY TAN
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  • 7.  RE: ReadAhead for rollback error message

    Posted 5 days ago
    Hi Casey,
    Thanks for the information! Is the APAR status still showing as 'OPEN' because it hasn't been updated? :)

    ------------------------------
    SangGyu Jeong
    Software Engineer
    Infrasoft
    Seoul Korea, Republic of
    ------------------------------



  • 8.  RE: ReadAhead for rollback error message

    Posted 4 days ago
    guess so :)

    The fix has went into 14.10.xC5 as well if you do a search on the APAR number.

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    CASEY TAN
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  • 9.  RE: ReadAhead for rollback error message

    InnerCircle
    Posted 9 days ago
    onlog -n 996907 > log996907

    grep "^6223d8 " log996907
    grep "^4cc6590 " log996907

    onlog -n 996908 > log996908

    grep "^ad6e2c " log996908
    grep "^215dbdc " log996908

    If one of these grep commands should not find its line, provide these entire onlog dumps (to support).

    ------------------------------
    Andreas Legner
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