Activating the Natural Buffer Pool on UNIX

This document covers the following topics:

General Information

Since the Natural buffer pool requires resources that should be created every time your system is booted, a procedure to activate the buffer pool should be called during system startup.

The Natural installation process provides a buffer pool start/stop service procedure. The name of the procedure will be generated depending on the installation directory.

Furthermore, the Natural installation process determines the platform automatically and prepares the system (V style or AIX) to execute the start/stop service procedure during start/stop of the system. Depending on the platform, the system directory for initialization and, if needed, the runlevel startup directories will be selected. The start/stop service procedure will be copied to the system directory for initialization and links will be created in the runlevel startup directories.

The Natural installation process installs the buffer pool start/stop service when sudoers permissions are available. You can also set up this service manually as described below, or you can use the script install_daemon_natbpsrv in the <install-dir>/Natural/INSTALL directory.

The Natural buffer pool needs some operating system resources for its operation. Therefore, kernel parameters need to be checked and, if necessary, increased as described below.

To verify the operation of the buffer pool, invoke the NATBPMON utility which is used to monitor the buffer pool's activity.

Preparing the Startup Procedure

The procedure sag<install-dir-number>natbpsrv in the <install-dir>/Natural/INSTALL directory may be used as a script or script template to invoke the Natural buffer pool during system startup.

The Software AG Installer assigns an internal number to each installation directory. This is reflected by the notation <install-dir-number> in the above procedure name. The instructions below assume that you use an installation directory with the internal number 1. Therefore, the procedure name sag1natbpsrv is used. If you have several installation directories and if you want to copy scripts, you may need to adapt the number in the procedure name.

The following topics are covered below:

Preparing the System V Style Startup Procedure

To set up the system, proceed as described below:

  1. Log in as user "root".

  2. Copy the script sag1natbpsrv to the init.d system directory.

    In this description, init.d and rc3.d (see further below) stand for the relevant path for the platform you are using. The following table shows where the init.d and rc3.d directories are located on the various platforms.

    Platform System Directory for Initialization Runlevel Startup Directory
    Oracle Solaris /etc/init.d /etc/rc3.d
    HP-UX /sbin/init.d /sbin/rc3.d
    Linux /etc/init.d /etc/init.d/rc3.d or /etc/init.d/rc5.d

  3. If already available, create a backup copy of your current sag1natbpsrv file contained in the init.d directory (see the above table).

  4. If you do not use the default values, set the following environment variables in the sag1natbpsrv procedure:

    NAT_HOME Location where Natural was installed.
    NATADM The login name of the Natural system administrator responsible for this buffer pool. It is assumed that this administrator account is called "sag", and that the user ID is already known to the system. It does not have to be a user with root privileges.

    Note:
    The Bourne shell does not allow blanks before and after the equals sign in the lines to be customized.

  5. Create a link "S64sag1natbpsrv" to the sag1natbpsrv procedure in the rc3.d directory (see the above table).

    You may create a link to the buffer pool procedure in the runlevel 3 startup directory of your UNIX machine. The rc3.d directory contains several Bourne shell scripts or links to Bourne shell scripts that start with "S" followed by a number. The buffer pool uses the number "64". A lower number will be executed first. If you add a file or a link to this directory, the respective code is executed when the system changes to "multi-user mode".

When you are using a Natural Development Server, make sure that Natural Development Server is started after the buffer pool, and that it is stopped before the buffer pool.

Preparing the AIX Startup Procedure

To set up the system, proceed as described below:

  1. Log in as user root.

  2. Copy the script sag1natbpsrv to the etc system directory.

  3. If you do not use the default values, set the following environment variables in the sag1natbpsrv procedure:

    NAT_HOME Location where Natural was installed.
    NATADM The login name of the Natural system administrator responsible for this buffer pool. It is assumed that this administrator account is called "sag", and that the user ID is already known to the system. It does not have to be a user with root privileges.

    Note:
    The Bourne shell does not allow blanks before and after the equals sign in the lines to be customized.

  4. The /etc/inittab file supplies the script to the init command's role as a general process dispatcher. Therefore, enter a record with the sag1natbpsrv script in the /etc/inittab file using the mkitab command. For example: 

    mkitab "sag1natbpsrv:3:wait:/etc/sag1natbpsrv > dev/console"

  5. Verify your changes to make sure that the changes made consist only of those changes desired.

Changing the Kernel Parameters

The information below applies to Oracle Solaris, HP-UX and Linux.

Note:
Since AIX dynamically adjusts the IPC configuration, kernel parameter changes are not required.

The Natural buffer pool needs the following operating system resources for its operation:

  • A set of semaphores to enable synchronization between the users.

  • Shared memory to store the buffer pools objects.

The amount of available shared memory and the semaphores are configured in the kernel. For information on how to change your current kernel, contact your system administrator or consult your respective operating system documentation.

Note:
Since semaphores are also needed to synchronize the access to Natural system files, additional operating system resources should also be considered here.

The following abbreviations are used:

NBP Number of buffer pools running on one computer.
SMU Sum of all "maximum users" assignments for all buffer pools.
MAXMEM Largest buffer pool size value for all buffer pools.
NSF Number of system files used.

If you have only one buffer pool on your computer, the following values are used:

NBP 1
SMU "Maximum users" assignment from the buffer pool assignments in the local configuration file.
MAXMEM Buffer pool size from the buffer pool assignments in the local configuration file.

As not all resources defined by the default parameter settings are used during normal system operation, the default values are sufficient to operate one buffer pool supporting up to 20 users using about 1 MB of memory.

Note:
You can find the default values specific to your environment in your kernel configuration file. Do not decrement any kernel parameters that are above their default values, as other software may need the larger value.

Change the following kernel parameters to the required values as follows:

Name Required Value
SEMAEM * Must be at least SMU.
SEMMNI Increment by (NBP + NSF).
SEMMNS Increment by (SMU + 5 * NBP) + NSF.
SEMMNU * Increment by SMU.
SEMMSL Must be at least SMU + 4.
SEMUME * Must be at least 5.
SEMVMX * Must be at least SMU.
SHMMAX Must be at least MAXMEM.
SHMMNI Increment by NBP.
SHMSEG Must be at least 4.

* Cannot be modified on Linux.

Review the changes made to the file sag1natbpsrv in your init.d directory in case the startup message is not displayed during rebooting.

Note:
If the system should fail to boot after modification (that is, the new kernel cannot be booted), check if there is an error in the startup procedure. Detailed information about trouble-shooting the operating system can be found in your respective operating system manuals. If you cannot solve the problem, contact Software AG support.