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  1. #1
    Join Date
    Dec 2007
    Posts
    7

    Unanswered: Huge slowdowns after 20 concurrent users

    Hello everyone,

    My userbase is experiencing slowdowns when hitting 20 concurrent connections. This is an AIX platform running db2 v8. I first thought perhaps it had something to do with a rogue sql statement that was hogging resources. After exhausting that I am at a loss.

    The operating system is running just fine, no bottlenecks. I have also ran many different snapshots and do not see any immediate issue with DB2.

    Could anybody suggest where I might look for? I think the key is 20 concurrent users, because it absolutlely only slows down when the 21st user logs in. Thoughts?

    Thank you

    Darren Bridle

  2. #2
    Join Date
    Sep 2006
    Posts
    97
    What about runstats and reorgs??? (if you had lot trsanction before if you didn't perform runsts and reorgs)

    try it out let us know

  3. #3
    Join Date
    May 2003
    Location
    USA
    Posts
    5,737
    What kind of connection pooling do you have on the application tier?
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

  4. #4
    Join Date
    Dec 2007
    Posts
    7
    I could do a runstats and reorg, does that have to be done when the users are not using the system?

    My apologies, how do I find out about connection pooling?

  5. #5
    Join Date
    Jun 2003
    Location
    Toronto, Canada
    Posts
    5,516
    Provided Answers: 1
    Quote Originally Posted by dbridle

    The operating system is running just fine, no bottlenecks. I have also ran many different snapshots and do not see any immediate issue with DB2.
    Then what IS slowing down?
    ---
    "It does not work" is not a valid problem statement.

  6. #6
    Join Date
    Dec 2007
    Posts
    7
    Thats a good question, I'm stumped. My DB2 expertise only really goes so far.

  7. #7
    Join Date
    Jun 2007
    Posts
    66
    Do a db2 get dbm cfg | grep -i agent


    Check for the values for the following parameters::


    Max number of existing agents (MAXAGENTS) =
    Agent pool size (NUM_POOLAGENTS) =
    Initial number of agents in pool (NUM_INITAGENTS) = 0
    Max number of coordinating agents (MAX_COORDAGENTS) = MAXAGENTS
    Max no. of concurrent coordinating agents (MAXCAGENTS) = MAX_COORDAGENTS
    Max number of client connections (MAX_CONNECTIONS) = MAX_COORDAGENTS

  8. #8
    Join Date
    Dec 2007
    Location
    Richmond, VA
    Posts
    1,328
    Provided Answers: 5
    With as little info as you have given and your not seeing excessive use of CPU/memory, then what about locking contention?

  9. #9
    Join Date
    Jan 2003
    Posts
    1,605
    Hi,
    I think Marcus_A has pointed out good question. Are you sure DB2 is the problem? What kind of application are you using? Are you using WebSphere Application Server? If so contact WAS admin to check out how connection pooling is set on WAS! If connection pooling is not set to process all 20 or 21 users at time, there could be bottle neck at WAS. Please write more info about your application and how does it connect to DB2.

    I suggest you to download "DB2 Monitor" tool from http://members.tripod.com/chuzhoi_files/index.html it is freeware. It requires Windows on client (I assume you are using Windows workstation) and any of Linux/Unix/Windows on server. Download the version of you DB2 Client - if you are using v8 client then download version 8, not version 9! The version you have on client execute command db2level.

    Then from Monitor menu select Locks and look if there are any locks on system.

    Then go to Monitor | Application and see if there is something suspicious. Right click on window and select Show lock dependencies. On right site of the window there will be displayed all application dependencies.

    There are a lot of other options. DB2 Monitor is just a good GUI tool to get all the info you could get from "db2 get snapshoot command", but this command will produce text based interface which is little bit too much for beginner.

    Hope this helps,
    Grofaty

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