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Thread: How many Semaphores needed?

  1. #1
    Join Date
    Oct 2000

    How many Semaphores needed?

    For Oracle Enterprise Server
    We are working on getting a new HP-UX 11i (64-bit) server and need to know the semaphore requirements for the unix group.
    As per Oracle's recommendation for each instance -

    Semaphores = ((value of processes in init file)*2) + a few for Oracle's internal use.

    My questions are -

    # is the equation same for 64-bit OS (and database)?
    Is this a good estimate depending upon if I estimated my processes correctly for all the instances?

    # Does this number change with Oracle 9i?

    - Rajeev
    Rajeev Suri

  2. #2
    Join Date
    Mar 2002
    Mesa, Arizona
    I'd suggest these values for HP/UX 11i (64-bit). We have used the same values on HP/UX 10.2 (32-bit) on 7.x, 8.x, and 9.x without problems.

    SEMMNI 4096
    SEMMNU (NPROC - 4)
    SEMVMX 32768
    SHMMAX Available physical memory
    SHMMNI 512
    SHMSEG 32

    Here's a few that have bit us in the past:
    NPROC 4000
    MAXUPRC ((NPROC*9)/10)
    NFILE (15 * NPROC + 2048)
    NFLOCKS 4096

    You didn't ask for it, but .. Best of luck .. on your migration to Linux. (just poking fun)

    "I do not fear computers. I fear the lack of them." Isaac Asimov
    Oracle Scirpts DBA's need

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