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  1. #1
    Join Date
    Sep 2003
    Posts
    51

    Unanswered: Instance startup

    Hi ALL,

    i tried to startup an instance and got ORA-27123. What happened ? Can anyone explain me what I'm suppose to do to work aroud this error ?

    Thanks

    Antoino Freitas

  2. #2
    Join Date
    Aug 2003
    Location
    Where the Surf Meets the Turf @Del Mar, CA
    Posts
    7,776
    Provided Answers: 1
    Please ALWAYS provide Oracle version, OS & OS version.
    =====================================
    27123, 00000, "unable to attach to shared memory segment"
    // *Cause: shmat() call failed
    // *Action: check permissions on segment, contact Oracle support
    I "assume" this is on some flavor of Unix.
    If so, the most likely cause is that one or more entries in /etc/system is too small or missing.

  3. #3
    Join Date
    Sep 2003
    Posts
    51
    Hi all,

    sorry I did not give all informations :

    Oracle version : Oracle8i Enterprise Edition Release 8.1.7.4.0

    OS : AIX 5.2

    Server IBM AIX RISC System/6000

    ORA-27123: unable to attach to shared memory segment
    IBM AIX RISC System/6000 Error: 22: Invalid argument

    I know what this error means, i've already look at the error message manual, I want to know the possibles causes.

    Antonio Freitas

  4. #4
    Join Date
    Aug 2003
    Location
    Where the Surf Meets the Turf @Del Mar, CA
    Posts
    7,776
    Provided Answers: 1
    AIX is not configured the way Oracle needs it to be setup.
    Go find the AIX Installation Guide & then do what it says.

  5. #5
    Join Date
    Nov 2003
    Location
    Bangalore, INDIA
    Posts
    333

    Thumbs up

    Hi ,

    The reason why this error occurs is because something is using the memory address that is SGA is trying to attach. The SGA begin address by default is 0x80000000.

    The user stack might use the space that SGA wants. You can also check ulimit to see the user stack size .

    The default size for stack is 8k and that should be sufficient unless you have application that requires a bigger stack size. If the stack size is using the space that is overlapping the SGA space, then you will need to change the SGA begin address.
    SATHISH .

  6. #6
    Join Date
    Sep 2003
    Posts
    51
    Hi,

    the command ulimit returns :
    ucam04:/ucam04/oracle817:Producao>ulimit -a
    time(seconds) unlimited
    file(blocks) unlimited
    data(kbytes) unlimited
    stack(kbytes) 65536
    memory(kbytes) unlimited
    coredump(blocks) unlimited
    nofiles(descriptors) 2000

    so the problem is not with my stack parameter. I'm working on tjis problema.

    Thanks

  7. #7
    Join Date
    Apr 2003
    Location
    Greenville, SC (USA)
    Posts
    1,155
    Semaphores ???

  8. #8
    Join Date
    Jul 2003
    Posts
    2,296
    Originally posted by gbrabham
    Semaphores ???
    I agree. When in doubt it is usually a semaphore problem.
    Try reducing the db parameter PROCESSES to something low like 100

    OR alter your AIX system to allocate more semaphores to oracle (that would be the more technical way of solving the problem).
    - The_Duck
    you can lead someone to something but they will never learn anything ...

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