Informix

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  • 1.  ReadAhead for rollback error message

    Posted 5 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 3 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 2 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 yesterday
    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 21 hours ago
    Edited by SangGyu Jeong 21 hours 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

    InnerCircle
    Posted 3 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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