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  1. #1
    Join Date
    Jan 2004
    Posts
    3

    Unanswered: Informix warnings (Aborting long transactions)

    Hello,

    I encountered 3 main problems while using Informix ver 7.31 probably due to bad configuration. Trying to correct the configuration doesn't help.
    The 3 main warnings I get (In <informix-user>.log are:

    1. WARNING! Physical Log size 4700 is too small.
    Physical Log overflows may occur during peak activity.
    Recommended minimum Physical Log size is 20 times maximum
    concurrent user threads.

    (Note: I didn't succeed to make HPSYLOG bigger. It said something like:
    Cannot Allocate Physical Log File, 2000 wanted, 1189 available.)

    2. Aborting Long Transaction: tx 0xc61a458 username: informix uid: 6
    (Do I have to change configuration for that, and How can I know in which transaction is happens)

    3. In addition there appeared this warning in con<informix-user>.log:
    <<Informix Dynamic Server>>> WARNING!
    Buffer pool size may cause Dynamic Server to get into
    a locked state. Recommended minimum buffer pool size is
    4 times maximum concurrent user threads.

    Attached is my onconfig file.
    Attached Files Attached Files

  2. #2
    Join Date
    Jan 2004
    Location
    San Antonio, Texas
    Posts
    47

    Wink Re: Informix warnings (Aborting long transactions)

    Hello,
    First you need to get your physical log (plog) out of your rootdbs into it's own space (plogdbs). The reason you are seeing that message is because you no longer have enough availabel space in rootdbs to extent the plog to what you want. Also keep in mind that if your plogdbs is 51200, you log cannot be the same it would need to be something like 51100.

    Second you should see something like this in the columns for your transaction.
    a14dae8 X-RP--- 6 Informix 1 a3269f8 0 3 0 0
    Once the transaction reaches the Long Transaction High Water mark (LTXHWM) it will start to rollback and other processing will continue. When the Long Trans Exclusive High Water Mark is reached all processing will stop until the one process has rolled back. This is governed by the following parameters in your onconfig:
    LTXHWM 50 # Long transaction high water mark percentage
    LTXEHWM 60 # Long transaction high water mark (exclusive)
    Now, do you need to change this, well it depends on several things. Are you users not commiting enough, are there too many long running transaction (pdq), or do you not have enough llogs?
    I wrote a detailed explanation of this for my company. I will try to find it and give it to you because it is just too much to write again.

    You should put your buffers back to 16 or 8.

    I noticed you SHMVIRTSIZE is very small. If you have messages in your logs that say "Dynamically added" and it's talking about a memory segment you should add them all up and increase SHMVIRTSIZE to that plus 10 - 20% more.

    I would also look at you PDQ. It is set to 100 and a maximum of 32 queries. That could be a nightmare if it is being used.

    Regards,
    DBAgirl

    Originally posted by ralgor
    Hello,

    I encountered 3 main problems while using Informix ver 7.31 probably due to bad configuration. Trying to correct the configuration doesn't help.
    The 3 main warnings I get (In <informix-user>.log are:

    1. WARNING! Physical Log size 4700 is too small.
    Physical Log overflows may occur during peak activity.
    Recommended minimum Physical Log size is 20 times maximum
    concurrent user threads.

    (Note: I didn't succeed to make HPSYLOG bigger. It said something like:
    Cannot Allocate Physical Log File, 2000 wanted, 1189 available.)

    2. Aborting Long Transaction: tx 0xc61a458 username: informix uid: 6
    (Do I have to change configuration for that, and How can I know in which transaction is happens)

    3. In addition there appeared this warning in con<informix-user>.log:
    <<Informix Dynamic Server>>> WARNING!
    Buffer pool size may cause Dynamic Server to get into
    a locked state. Recommended minimum buffer pool size is
    4 times maximum concurrent user threads.

    Attached is my onconfig file.

  3. #3
    Join Date
    Jan 2004
    Posts
    3

    Re: Informix warnings (Aborting long transactions)

    Thank you very much, I'll try to implement it. especially increasing toodbs.

    Ruth


    Originally posted by DBAgirl
    Hello,
    First you need to get your physical log (plog) out of your rootdbs into it's own space (plogdbs). The reason you are seeing that message is because you no longer have enough availabel space in rootdbs to extent the plog to what you want. Also keep in mind that if your plogdbs is 51200, you log cannot be the same it would need to be something like 51100.

    Second you should see something like this in the columns for your transaction.
    a14dae8 X-RP--- 6 Informix 1 a3269f8 0 3 0 0
    Once the transaction reaches the Long Transaction High Water mark (LTXHWM) it will start to rollback and other processing will continue. When the Long Trans Exclusive High Water Mark is reached all processing will stop until the one process has rolled back. This is governed by the following parameters in your onconfig:
    LTXHWM 50 # Long transaction high water mark percentage
    LTXEHWM 60 # Long transaction high water mark (exclusive)
    Now, do you need to change this, well it depends on several things. Are you users not commiting enough, are there too many long running transaction (pdq), or do you not have enough llogs?
    I wrote a detailed explanation of this for my company. I will try to find it and give it to you because it is just too much to write again.

    You should put your buffers back to 16 or 8.

    I noticed you SHMVIRTSIZE is very small. If you have messages in your logs that say "Dynamically added" and it's talking about a memory segment you should add them all up and increase SHMVIRTSIZE to that plus 10 - 20% more.

    I would also look at you PDQ. It is set to 100 and a maximum of 32 queries. That could be a nightmare if it is being used.

    Regards,
    DBAgirl

  4. #4
    Join Date
    Jan 2004
    Location
    San Antonio, Texas
    Posts
    47

    Cool Re: Informix warnings (Aborting long transactions)

    Here is the document I wrote for our Bank deveopers to understand LTXHWM. I hope it is helpful. Attached

    Regards,
    DBAgirl

    Originally posted by ralgor
    Thank you very much, I'll try to implement it. especially increasing toodbs.

    Ruth
    Attached Files Attached Files

  5. #5
    Join Date
    Nov 2003
    Location
    Mumbai, India
    Posts
    92
    Hi ralgor,

    Quote:
    2. Aborting Long Transaction: tx 0xc61a458 username: informix uid: 6

    I too have, written a FAQ on how to prevent Long Transactions from developing in tek-tips Informix IDS Forum. You can have a look at:

    http://www.tek-tips.com/faqs.cfm?spid=179&sfid=2537

    Regards,
    Shriyan

  6. #6
    Join Date
    Jan 2004
    Posts
    3

    Re: Informix warnings (Aborting long transactions)

    Thanks a lot. It really explains things.

    Ruth
    Originally posted by DBAgirl
    Here is the document I wrote for our Bank deveopers to understand LTXHWM. I hope it is helpful. Attached

    Regards,
    DBAgirl

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