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  1. #1
    Join Date
    Jul 2012
    Posts
    16

    Unanswered: DB2 - high system memory usage (Windows)

    Hi,

    We have DB2 (9.5 LUW) installed on windows server. Few days ago we've noticed the system memory usage suddenly increased from 10 GB used to almost 16 GB used (of 16 GB total). This happened in a very short time of 30 minutes. The situation lasted for several hours until I started a full online database backup (to TSM). As soon as the backup process started, the mem usage immediately drops back to normal 10 GB used in just a few minutes. After a day the usage rised again to about 95-97% of total system physical memory.
    The fact that database backup solved the memory problem temporarily, I think points to the core of the problem, but unfortunatelly I not very familiar with memory monitoring on DB2 so I cannot tell which segment caused the trouble. I hope someone can give me a hint where to start to look. Please, advise me what additional information should I collect on the db2 and I will post this here.

    I would kindly ask for some help.

    Thanks in advance.
    BR,
    Domen

  2. #2
    Join Date
    Jul 2012
    Posts
    16
    Quote Originally Posted by domenm View Post
    Hi,

    We have DB2 (9.5 LUW) installed on windows server. Few days ago we've noticed the system memory usage suddenly increased from 10 GB used to almost 16 GB used (of 16 GB total). This happened in a very short time of 30 minutes. The situation lasted for several hours until I started a full online database backup (to TSM). As soon as the backup process started, the mem usage immediately drops back to normal 10 GB used in just a few minutes. After a day the usage rised again to about 95-97% of total system physical memory.
    The fact that database backup solved the memory problem temporarily, I think points to the core of the problem, but unfortunatelly I not very familiar with memory monitoring on DB2 so I cannot tell which segment caused the trouble. I hope someone can give me a hint where to start to look. Please, advise me what additional information should I collect on the db2 and I will post this here.

    I would kindly ask for some help.

    Thanks in advance.
    BR,
    Domen

    OK, just so resum the whole thing with two questions:

    1. how to find out which part of DB2 is causing this sudden mem usage?
    2. why is the memory freed when backup started?

    D.

  3. #3
    Join Date
    Jun 2003
    Location
    Toronto, Canada
    Posts
    5,516
    Provided Answers: 1
    The commands that can show memory usage: db2mtrk, db2pd -mempools, db2pd -memsets. Details in the manual.
    ---
    "It does not work" is not a valid problem statement.

  4. #4
    Join Date
    Jul 2012
    Posts
    16
    Quote Originally Posted by n_i View Post
    The commands that can show memory usage: db2mtrk, db2pd -mempools, db2pd -memsets. Details in the manual.
    Hi n_i,

    thanks for your response. I have collected the mem data as you suggested, but as I look at the numbers I cannot see anything strange that would explain such drastic memory drop. I don't have much experiences with this so I'm probably missing something important here. I put the results in the attachment, I'd like to ask you to take a quick look if you can see something wrong.

    I appreciate your help.
    Regards,
    D.

    db2mtrk_a.txtdb2mtrk_av.txtdb2mtrk_i.txtdb2pd_mempools.txtdb2pd_memsets.txt

  5. #5
    Join Date
    Jun 2003
    Location
    Toronto, Canada
    Posts
    5,516
    Provided Answers: 1
    To see "anything strange", as you say, you'd probably need to compare the memory use information collected at two points in time: before and after the alleged change of utilization. Don't forget to collect the data for database pools -- they seem to be missing from your files.
    ---
    "It does not work" is not a valid problem statement.

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