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  1. #1
    Join Date
    Jun 2011
    Posts
    9

    Question Unanswered: DB2 + Swap Memory Usage.

    Hey Guys,

    Sorry new to this forum and new to DB2/Lunux so please bare with me.

    I have a server that consists of 2 instances, One has 8 databases and One has 2 databases.

    I have STMM set to on for everything and wondering what i have configured wrong or what i can do to make sure db2 stops getting killed by the OS for using all the swap.

    Im Running DB2 9.7.2 on RHEL 6

    free shows :
    total used free shared buffers cached
    Mem: 5142160 5099108 43052 0 12604 968012
    -/+ buffers/cache: 4118492 1023668
    Swap: 779880 779864 16

    db2pd -dbptnmem shows:
    Instance 1
    Memory Limit: 4164804 KB
    Current usage: 2806336 KB
    HWM usage: 2808576 KB
    Cached memory: 1498624 KB

    Instance 3
    Memory Limit: 4164804 KB
    Current usage: 780032 KB
    HWM usage: 785152 KB
    Cached memory: 398528 KB

    One thing i have found through searching is that my tablespaces are created with:
    FILE SYSTEM CACHING;

    Could this be the issue, or is there something else i need to look at?

    These are all pretty small databases on the guest mostly containing work tables for software.

    Any help would be fantastic.

    Thanks in Advance.

  2. #2
    Join Date
    May 2003
    Location
    USA
    Posts
    5,737
    I would upgrade to FP4, and turn file system caching off except for SMS temporary tablespaces. But in general, DB2 seems to have memory problems with Linux, at least more than on AIX.
    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
    Jun 2011
    Posts
    9
    On Further investigation i have found that these particular processes are using alot of virtual memory.

    Google is not being that helpful.

    top - 14:03:31 up 3 days, 2:10, 2 users, load average: 0.33, 0.51, 0.44
    Tasks: 119 total, 2 running, 117 sleeping, 0 stopped, 0 zombie
    Cpu : 3.7%us, 3.3%sy, 0.0%ni, 90.0%id, 1.0%wa, 0.0%hi, 0.3%si, 1.7%st
    Mem: 5142160k total, 5094752k used, 47408k free, 5368k buffers
    Swap: 779880k total, 779856k used, 24k free, 940676k cached

    PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
    2161 root 15 0 1800m 1.2g 9232 S 0.0 23.8 1:56.19 db2syscr
    2162 root 15 0 1799m 1.2g 9232 S 0.0 23.8 1:55.88 db2syscr
    2163 root 15 0 1800m 1.2g 9232 S 0.0 23.7 1:56.04 db2syscr

    Thanks in advance

  4. #4
    Join Date
    Jun 2003
    Location
    Toronto, Canada
    Posts
    5,516
    Provided Answers: 1
    Set INSTANCE_MEMORY for both instances such that together they amount to 75% of the server physical memory (provided that nothing else is running on the server). Set each database memory to AUTOMATIC.

  5. #5
    Join Date
    Jun 2011
    Posts
    9
    Thanks Guys,

    Ill try both of the above.

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