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documentation.suse.com / SUSE Linux Enterprise Server-Dokumentation / System Analysis and Tuning Guide / Kernel tuning / Tuning SUSE Linux Enterprise for SAP
Applies to SUSE Linux Enterprise Server 15 SP4

17 Tuning SUSE Linux Enterprise for SAP

This chapter presents information about preparing and tuning SUSE Linux Enterprise Server to work optimally with SAP applications with sapconf. sapconf is for SUSE Linux Enterprise systems that install SAP applications. Customers who have SUSE Linux Enterprise Server for SAP Applications should use saptune.

Note: The sapconf command has been removed

In SUSE Linux Enterprise Server and SUSE Linux Enterprise Server 11 and 12, the sapconf command was included in the package with the same name.

For SUSE Linux Enterprise Server and SUSE Linux Enterprise Server 15, this has been changed: The command sapconf has been removed from the sapconf package. The package contains a systemd service only. There is no sapconf command line tool anymore, no sapconf/tuned profiles, and no tuned.

17.1 Tuning SLE Systems with sapconf 5

The package sapconf is available in SUSE Linux Enterprise Server and SUSE Linux Enterprise Server for SAP Applications. It sets recommended parameters for the following types of SAP applications: SAP NetWeaver, SAP HANA, and SAP HANA-based applications.

Overview of sapconf5 in SUSE® Linux Enterprise Server 12
sapconf5 (without tuned)
  • sapconf-netweaver (sapconf profile as a replacement for tuned profile)

  • sapconf-hana (sapconf profile as a replacement for tuned profile)

  • sapconf-bobj (sapconf profile as a replacement for tuned profile)

  • sapconf-ase (sapconf profile as a replacement for tuned profile)

Overview of sapconf5 in SUSE® Linux Enterprise Server 15
sapconf5 (without tuned)

no profiles anymore

Note that if you previously made changes to the system tuning, those changes may be overwritten by sapconf.

sapconf 5 ships a systemd service which applies the tuning and ensures that related services are running.

To use sapconf, make sure that the package sapconf is installed on your system.

Note: No profiles in SUSE Linux Enterprise Server and SUSE Linux Enterprise Server 15 SP4

In SUSE Linux Enterprise Server and SUSE Linux Enterprise Server 15, sapconf no longer supports profiles.

17.1.1 Verifying sapconf setup

With sapconf 5.0.2 and up, the check tool sapconf_check is available, which verifies the correct setup of sapconf. For example:

# sapconf_check
This is sapconf_check v1.0.
It verifies if sapconf is set up correctly and will give advice to do so.
Please keep in mind:
{{ - This tool does not check, if the tuning itself works correctly.}}
{{ - Follow the hints from top to down to minimize side effects.}}
Checking sapconf
[ OK ] sapconf package has version 5.0.2
[ OK ] saptune.service is inactive
[ OK ] saptune.service is disabled
[WARN] tuned.service is enabled/active with profile 'virtual-guest -> Sapconf does not require tuned! Run 'systemctl stop tuned.service', if not needed otherwise.
[FAIL] sapconf.service is inactive -> Run 'systemctl start sapconf.service' to activate the tuning now.
[FAIL] sapconf.service is disabled -> Run 'systemctl enable sapconf.service' to activate sapconf at boot.1 warning(s) have been found.
2 error(s) have been found.
Sapconf will not work properly!

If sapconf_check finds problems, it will give hints on how to resolve the issue. The tool will not verify whether the system has been tuned correctly. It only checks that sapconf is set up correctly and has been started.

17.1.2 Enabling and disabling sapconf and viewing its status

After the installation of sapconf, the sapconf service is enabled.

You can inspect or change the status of sapconf as described in the following:

  • To see the status of the service sapconf:

    # systemctl status sapconf

    The service should be displayed as active (exited).

  • To start the service sapconf:

    # systemctl start sapconf
  • Should sapconf be disabled, enable and start it with:

    # systemctl enable --now sapconf
  • To stop the service sapconf:

    # systemctl stop sapconf

    This command will disable the vast majority of optimizations immediately. The only exceptions from this rule are options that require a system reboot to enable/disable.

  • To disable sapconf, use:

    # systemctl disable sapconf

    If you have not specifically enabled any of the services that sapconf depends on yourself, this will also disable most tuning parameters and all services used by sapconf.

Tip: Additional services that sapconf relies on

In addition to the sapconf service it also relies on the following two services:

  • sysstat which collects data on system activity.

  • uuidd which generates time-based UUIDs that are guaranteed to be unique even in settings where many processor cores are involved. This is necessary for SAP applications.

17.1.3 Configuring sapconf5

In general, the default configuration of sapconf already uses the parameter values recommended by SAP. However, if you have special needs, you can configure the tool to better suit those.

All parameters of sapconf can be found in the file /etc/sysconfig/sapconf. The file can be edited directly. All parameters in this file are explained by means of comments and references to SAP Notes, which can be viewed at https://launchpad.support.sap.com/.

When sapconf is updated, all customized parameters from this file will be preserved as much as possible. However, sometimes parameters cannot be transferred cleanly to the new configuration file. Therefore, after updating it is advisable to check the difference between the previous custom configuration, which during the update is moved to /etc/sysconfig/sapconf.rpmsave, and the new version at /etc/sysconfig/sapconf.

Log messages related to this file are written to /var/log/sapconf.log.

When editing either of these files, you will find that some values are commented by means of a # character at the beginning of the line. This means that while the parameter is relevant for tuning, there is no suitable default for it.

Conversely, you can add # characters to the beginning of the line to comment specific parameters. However, you should avoid this practice, as it can lead to sapconf not properly applying the profile.

To apply edited configuration, restart sapconf:

# systemctl restart sapconf

Confirming that a certain parameter value was applied correctly works differently for different parameters. Hence, the following serves as an example only:

Example 17.1: Checking Parameters

To confirm that the setting for TCP_SLOW_START was applied, do the following:

  • View the log file of sapconf to see whether it applied the value. Within /var/log/sapconf.log, check for a line containing this text:

    Change net.ipv4.tcp_slow_start_after_idle from 1 to 0

    Alternatively, the parameter may have already been set correctly before sapconf was started. In this case, sapconf will not change its value:

    Leaving net.ipv4.tcp_slow_start_after_idle unchanged at 1
  • The underlying option behind TCP_SLOW_START can be manually configured at /proc/sys/net.ipv4.tcp_slow_start_after_idle. To check its actual current value, use:

    # sysctl net.ipv4.tcp_slow_start_after_idle

17.1.4 Removing sapconf

To remove sapconf from a system, uninstall its package with:

# zypper rm sapconf

Note that when doing this, dependencies of sapconf will remain installed. However, the service sysstat will go into a disabled state. If it is still relevant to you, make sure to enable it again.

17.1.5 For more information

The following man pages provide additional information about sapconf:

  • Detailed description of all tuning parameters set by sapconf: man 5 sapconf

  • Information about configuring and customizing the sapconf profile: man 7 sapconf

Also see the blog series detailing the updated version of sapconf at https://www.suse.com/c/a-new-sapconf-is-available/.

17.1.6 Using tuned together with sapconf

With version 5, sapconf does not rely on tuned anymore. This means both tools can be used independently. sapconf will print a warning in its log if the tuned service is started.

Important: Using tuned and sapconf together

If you are going to use tuned and sapconf simultaneously, be very careful, that both tools do not configure the same system parameters.