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  1. #1
    Join Date
    Sep 2004
    Posts
    111

    Talking Unanswered: Physical Memory. DB2 does not see this

    Team,

    Any body knows why DB2 see only 71Mb memory free.
    When I start db2 using db2start command. I can see the below entry in the db2diag.log. And I COULD NOT ABLE TO ACTIVATE DB with 1GB bufferpool.

    DB2DIAG.log
    =====================
    Instance "db2inst1" uses "32" bits and DB2 code release "SQL08023"
    with level identifier "03040106".
    Informational tokens are "DB2 v8.1.3.96", "s050811", "MI00143", FixPak "10".
    DATA #2 : System Info, 436 bytes
    System: Linux Super88db 6 2 x86_64
    CPU: total:4 online:4 Cores per socket:2 Threading degree per core:1
    Physical Memory(MB): total:7974 free:71
    Virtual Memory(MB): total:32543 free:24557
    Swap Memory(MB): total:24569 free:24486
    Kernel Params: msgMaxMessageSize:65536 msgMsgMap:131072 msgMaxQueueIDs:9000
    msgNumberOfHeaders:131072 msgMaxQueueSize:131072
    msgMaxSegmentSize:16 shmMax:2800000000 shmMin:1
    shmIDs:4096
    shmSegments:4096 semMap:32000 semIDs:128 semNum:32000
    semUndo:32000 semNumPerID:250 semOps:2001 semUndoSize:20
    semMaxVal:32767 semAdjustOnExit:32767

    ACTIVATE COMMAND
    ===============================
    Super88db: >db2 activate db Mandb1
    SQL1478W The defined buffer pools could not be started. Instead, one small
    buffer pool for each page size supported by DB2 has been started.
    SQLSTATE=01626

    FREE command and TOP command
    ==============================
    Super88db: >free
    total used free shared buffers cached
    Mem: 8165012 539716 7625296 0 0 0
    -/+ buffers/cache: 539716 7625296
    Swap: 0 0 0

    Super88db: >top
    top - 13:08:48 up 6 days, 22:00, 2 users, load average: 0.00, 0.02, 0.00
    Tasks: 64 total, 1 running, 63 sleeping, 0 stopped, 0 zombie
    Cpu(s): 0.1%us, 0.1%sy, 0.0%ni, 99.8%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
    Mem: 8165012k total, 539796k used, 7625216k free, 0k buffers
    Swap: 0k total, 0k used, 0k free, 0k cached

    PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
    1 root 15 0 10348 688 580 S 0.0 0.0 0:00.58 init
    3177 db2inst1 16 0 34740 7732 4464 S 0.0 0.1 0:00.02 db2bp
    13750 db2inst1 15 0 10720 884 688 R 0.0 0.0 0:00.00 top
    17425 root 15 0 5908 740 544 S 0.0 0.0 0:00.43 syslogd
    17428 root 19 0 3800 432 344 S 0.0 0.0 0:00.00 klogd

    Fyi.. This is VM environment..

    Thanks
    U

  2. #2
    Join Date
    Jan 2003
    Posts
    4,292
    Provided Answers: 5
    You are using 32 bit DB2. It can only use about 1.7 GB of memory total.

    Andy

  3. #3
    Join Date
    Sep 2004
    Posts
    111

    Talking

    Here it is using/showing only 71mb. Why?
    Even I updated the INSTANCE_MEMORY dbm cfg to 1GB.. Still no luck

    -U

  4. #4
    Join Date
    May 2003
    Location
    USA
    Posts
    5,737
    I think you have a basic mis-understanding of how memory works in Linux. A significant amount of memory is allocated to disk caching by Linux if not needed by something else, and is given back (made free) as soon as DB2 or anything else needs it.

    You can use the top command and to see how much is used for disk cache by Linux.
    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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