ReadAhead for rollback error message

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 ------------------------------ #Informix

Open a PMR Case and report it. New to me. Worst case they tell you "No problem". ------------------------------ Art S. Kagel, President and Principal Consultant ASK Database Management Corp. www.askdbmgt.com ------------------------------

onlog -n 996907 > log996907grep "^6223d8 " log996907 grep "^4cc6590 " log996907 onlog -n 996908 > log996908grep "^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 ------------------------------

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 ------------------------------

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 ------------------------------

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 ------------------------------

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 ------------------------------ CASEY TAN ------------------------------

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 ------------------------------

guess so :) The fix has went into 14.10.xC5 as well if you do a search on the APAR number. ------------------------------ CASEY TAN ------------------------------