This document covers the following topics:

• About Activating the Natural Buffer Pool on Linux

• Changing the Kernel Parameters

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About Activating the Natural Buffer Pool on Linux

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 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 or it will create the unit files for systemd.

The Natural installation process installs the buffer pool start/stop service when sudoers permissions are available.

You can also use the script daemon.sh in the <install-dir>/common/bin directory (see also the documentation Installing Software AG Products, section Register Daemons to Automatically Start and Shut Down Products on Linux Systems). The used rc scripts are in <install-dir>/Natural/INSTALL/sys.

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.

Changing the Kernel Parameters

The information below applies to Linux.

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.

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.

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.