Configuring the shared memory and semaphores

On each managed system, shared memory and semaphores are required for data collection. The Agent requires one semaphore and one shared memory segment for each metric group per instance (instance refers to a system or an application collector). The default values of shared memory and semaphores are usually sufficient. 

If you are notified about inadequate shared memory and semaphore resources during Agent installation, you can configure these settings by performing the following steps:

 Configuration steps for UNIX and Solaris systems
  1. Log in as a root user to the computer where the Capacity Agent is installed.
  2. Open the /etc/system file and update values as described in the following table:

    Settings for IPC semaphores in the /etc/system file



    Recommendation for specifying a value


    semsys: seminfo_semmni

    Number of semaphore identifiers (semaphore sets) systemwide.

    Add (25 + 25 x the number of instances) to the current value.

    (An instance refers to a system or an application collector. Number of instances refers to the number of system and application collectors running on a computer.)

    If the current value of the computer is 100 and you have one system collector, set the value to 150.

    semsys: seminfo_semmsl

    Maximum number of semaphores per unique identifier.

    No specific recommendation. BMC TrueSight Capacity Optimization will attach two semaphores per identifier.

    semsys: seminfo_semopm


    No specific recommendation. This semaphore setting has no impact on the operation of BMC TrueSight Capacity Optimization.

    Ensure that the variable entries in the /etc/system file does not exceed 80 characters because the kernel might get disabled.

  3. Restart the computer for these updates to take effect.

 Configuration steps for Linux systems
  1. Log in as a root user to the Linux system where the Capacity Agent is installed.
  2. Access the following path that contains the kernel settings files: /proc/sys/kernel
  3. Update values in the following files as required: sem, shmall, shmmax, shmmni

    These updates affect the Linux kernel settings. Therefore, read the Linux documentation carefully before updating these files.

  4. Run the following command to check the shared memory settings:
    ipcs -l

  5. Restart the system.

 Configuration steps for HP systems
  1. Log in to the HP-UX system where the Agent is installed.
  2. At the UNIX prompt, enter the following command to open System Management Homepage (SMH).
  3. Select k -Kernel Configuration and press Enter.
  4. Select t - Tunables to view a list of configurable parameters, and press Enter.
  5. Select the parameter that you want to update, and press Enter.
  6. Press m and specify the updated values for the required parameters.
    A confirmation message about these modifications is displayed.
  7. Restart the system.

For more information, see  Kernel Parameters Configuration .

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