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  1. #1
    Join Date
    Apr 2004
    Posts
    36

    Arrow Unanswered: Lock Escalations

    UDB V8 fp5
    Solaris OS...


    We are seeing lots and lots of lock escalations in our prod..
    There was a crash od DB on last night.. I am thinking it is because of two
    many loack escalations..

    Any how can you guys give me how to get rid of these lock escalations.?

    Please give me a detailed explanation...

  2. #2
    Join Date
    May 2003
    Location
    USA
    Posts
    5,737
    Assuming you mean escalation from row lock to table lock:

    - Increase locklist db parmameter by a factor of 10.
    - Increase maxlocks db parameter to about 60 (percent).

    Locklist is the amount of memory allocated to store active locks. When this gets full, escalation occurs. Maxlocks is the percent of the locklist memory that any one application can use before escalation occurs. If 60 does not work, you can increase it more.
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

  3. #3
    Join Date
    Jan 2004
    Location
    Europe, Finland, Helsinki
    Posts
    64
    Yes, it's about memory usage!

    And of course, you can better the situation using PAGE LOCKS instead off row locks. With page locks memory usage is much lower, so escalations occurs no so offen.

    But this strategy has drawbacks, too...

    Cheers, Bill

  4. #4
    Join Date
    Jan 2004
    Location
    Tallahassee, FL, USA
    Posts
    96
    each x lock 1st lock uses 512 bytes, othe locks 32 bytes, calculate based on your maxappls .

    if your application user maxlock ( % of space used from locklist ) then lock escalations.

    either increase locklist ( lock memory) or increase maxlock ( % of lock utilize)



    while you getting escalations , get snapshot for DB & lock

    db2 get snapshot for database on Dbname > snpdb
    no of locks ,how much locklist user , no escalations, time out , based on it increase locklist , or maxlock


    db2 get snapshot for locks on DBname > snplck


    check which table are escalating

    if suspecting any application

    get snapshot for lock for application agentid handler



    Hope this will help


    Let me know , if any questions


    Thank You


    Lekharaju Ennam

  5. #5
    Join Date
    May 2003
    Location
    USA
    Posts
    5,737
    Quote Originally Posted by hurmavi
    And of course, you can better the situation using PAGE LOCKS instead off row locks. With page locks memory usage is much lower, so escalations occurs no so offen.
    Page locks are not available on DB2 for LUW, only with DB2 for OS/390 and z/OS.
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

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