Linux Setup Guide for Altibase

glibc Compatibility Version

Starting from Altibase 5.5.1, the compatibility is checked based on the glibc version.

The glibc versions with guaranteed compatibility for each Altibase server version are as follows.

glibc Recommended Version

THP(Transparent Huge Pages)

How to Change Kernel Parameters

Let's learn how to check and change the settings of each kernel parameter.

Change Immediately

Settings using the governor directive and the cpupower command can be changed while online, but initialized when the OS is restarted.

Governor directives using the cat command

cpupower

Permanent Application

This is a way to keep the settings even after restarting the OS.

1. rc.local: Applicable only on RHEL 6

Add the following line to the /etc/rc.local file:

2. Using udev rules: For RHEL 7 and above

Create or modify the file `/etc/udev/rules.d/99-cpufreq.rules`:

Add the following:

udevadm reload:

3. Using tuned : RHEL 7 and above

On RHEL 7 or later, a tuned profile configuration may be required.

Check the active tuned profile:

If the tuned service is stopped or there is no active profile, this step is not necessary. If tuned is active, check the current profile and apply the appropriate configuration.

Example:

Changing the profile configuration: Example when the currently active profile is the virtual-guest profile 

[main] Add the following to the session:

Using built-in Linux profiles like throughput-performance or latency-performance can have the following effects:

• The CPUfreq governor is set to performance.
• The CPU clock speed is fixed to the maximum.
  
  

Apply changed profile:

Alternatively, change the active profile to throughput-performance or latency-performance.

RemoveIPC

RemoveIPC applies to Red Hat Enterprise Linux 7.2 and later, and the recommended value is 'no'.

How to Check Set Value

Make sure RemoveIPC = no is set in the logind.conf file.

Check RemoveIPC settings

How to Change the Settings

Red Hat Enterprise Linux 7

Change Immediate

RemoveIPC does not provide a way to change immediately on Linux

Permanent Application

Open the /etc/systemd/logind.conf file with an editor and change RemoveIPC = no.

How to change RemoveIPC

Restart the OS or execute the following command to apply the changes.

Apply after changing RemoveIPC

swappiness

You can check the value of vm.swappiness in the following two ways.

1. checking /proc/sys/vm/swappiness file

example:

2. using sysctl comman

example:

3. Additional check for RHEL 8: Verify the vm.force_cgroup_v2_swappiness parameter

In a cgroup v1 environment on RHEL 8, the vm.swappiness setting has little effect on swap behavior, which may lead to unexpected swapping. To prevent this, an additional configuration recommended by Red Hat should be verified.

(Reference: https://access.redhat.com/solutions/6785021 )

Use the sysctl command to check the value of the parameter. The recommended value is 1.

example:

If the following result appears, it means the system does not support the vm.force_cgroup_v2_swappiness parameter, so you need to check setting number 4.

4. Additional check for RHEL 8 (vm.force_cgroup_v2_swappiness parameter not supported):memory.swappiness value of each cgroup

On RHEL 8 systems that do not support vm.force_cgroup_v2_swappiness, you need to verify the memory.swappiness value for each cgroup. All values should be set to 1.

example:

If a value other than 1 appears as shown below, you need to change the memory.swappiness value of all cgroups to 1.

How to change the swappiness setting

Change Immediate

Permanent Application

The following method ensures the setting is retained even after rebooting the OS. To fully apply the configuration, the OS must be restarted.

1. Modify the default sysctl.conf file

Add the following setting or modify the existing value.

2. Create /etc/sysctl.d/99-sysctl.conf or modify the existing file.

Add the following setting or modify the existing value.

3. Additional setting for RHEL 8: vm.force_cgroup_v2_swappiness = 1

Add the following to both /etc/sysctl.d/99-sysctl.conf and /etc/sysctl.conf.

4. Additional setting for RHEL 8 (vm.force_cgroup_v2_swappiness parameter not supported): Change the memory.swappiness value of each cgroup to 1

Support for the vm.force_cgroup_v2_swappiness parameter in RHEL 8 may vary depending on the version.
For unsupported versions, it is recommended to contact the OS vendor for guidance on Workaround #2 described on the following page. 

• Red Hat Solution: 6785021

5. Using tuned: RHEL 7 and above

On RHEL 7 or later, configuring a tuned profile may be necessary.

Check the active tuned profile:

If the tuned service is stopped or there is no active profile, this step is not required. If tuned is active, check the current profile and apply the appropriate settings..

example:

Changing the profile configuration: Example when the currently active profile is throughput-performance

If there is a vm.swappiness setting in the [sysctl] session, modify it; if not, leave it as is.

If vm.force_cgroup_v2_swappiness is supported on RHEL 8, also add the following setting to the [sysctl] session.

Apply the changed profile:

THP

Check the current settings, and if the recommended configuration is not applied, refer to the guide below to make the changes.

Check THP settings

Verify the following three items to confirm that THP is disabled.

1. Check the current status of THP

Red Hat Enterprise Linux 6

Recommended settings: never

The values enclosed in brackets ([]) in the output indicate the current settings.

2. Check /proc/meminfo

Example output: All values except Hugepagesize should be 0.

3. Check the boot loader settings

Example output: Verify that transparent_hugepage=never and transparent_hugepage.defrag=never are present.

How to change THP settings

To fully disable THP (Transparent Huge Pages), it is recommended to also change the defrag setting. If defrag is set to always, even with THP disabled, the kernel may still try to defragment fragmented memory when allocating large pages, which can cause unnecessary CPU usage and performance degradation.

Temporary application

The commands below will stop creating and using new THP. Previously created THP will not be released, and to completely remove them, you need to reboot the OS with THP disabled.

Red Hat Enterprise Linux 6

Red Hat Enterprise Linux 7 and above

Permanent application

The following settings are for maintaining the configuration even after rebooting the OS. To fully apply the changes, the OS must be restarted.

1. modify GRUB settings

modify grub.conf :

Red Hat Enterprise Linux 6 (/etc/grub.conf 수정)

RHEL 6 modification example: Add transparent_hugepage=never transparent_hugepage.defrag=never to the end of the kernel line.

Red Hat Enterprise Linux 7 and above (modify /etc/default/grub.conf)

RHEL 7 and later modification example: Add transparent_hugepage=never transparent_hugepage.defrag=never at the end of the GRUB_CMDLINE_LINUX entry.

Regenerate the GRUB configuration file::

- BIOS-based systems:

- UEFI-based systems:

OS reboot:

Reboot the OS to apply the changes.

2. Add rc.local configuration (RHEL 6 only)

Add the following content at the end of the file.

3. Using tuned: RHEL 7 and above

On RHEL 7 or later, configuring a tuned profile may be necessary.

Check the active tuned profile:

If the tuned service is stopped or there is no active profile, this step is not needed. If tuned is active, check the current profile and apply the settings.

example:

Changing the profile configuration: Example when the currently active profile is throughput-performance

If there is a transparent_hugepage setting in the [vml] session, modify it; if not, leave it as is.

Apply the changed profile:

Restart the OS to confirm the changes. The OS reboot can be done once after all kernel parameter changes are made.

max_map_count

Check the current settings, and if the recommended configuration is not applied, refer to the guide below to make the necessary changes.

1. Using cat 

2. Using sysctl

How to change the max_map_count setting

Temporary application

Permanent application 

The following method ensures the setting is retained even after rebooting the OS. To fully apply the configuration, the OS must be restarted.

1. Modify the default sysctl.conf file

Add vm.max_map_count = 2147483647 or modify the existing value.

2. Add rc.local configuration (RHEL 6 only)

Add the following content at the end of the file.

3. Using tuned: RHEL 7 and above

On RHEL 7 or later, configuring a tuned profile may be necessary.

Check the active tuned profile:

If the tuned service is stopped or there is no active profile, this step is not required. If tuned is active, check the current profile and apply the appropriate settings.

example:

Changing the profile configuration: Example when the currently active profile is throughput-performance

If there is a max_map_count setting in the [sysctl] session, modify it; if not, leave it as is.

Apply the changed profile.

Shared Memory and Semaphore

How to Check Set Value

lpcs command

How to check shared memory and semaphore 1 - Using ipcs command

sysctl command

How to check shared memory and semaphore 2 - Using sysctl command

How to Change the Settings

Change Immediately

Use the echo command.

Immediate change shared memory and semaphores

Permanent Application

Add to /etc/sysctl.conf file.

Shared memory and semaphore permanent application - /etc/sysctl.conf

User Setting

This section describes the user settings required to install and operate the Altibase server on Linux. A user is an OS user, and is a user who installs the Altibase server and runs the Altibase server process.

The user login configuration file in the bash shell is .bash_profile. The user configuration file differs depending on the shell, but it is described based on the Linux default shell because it is a bash shell.

The user setting is divided into the following two categories:

• Resource limitation

• Environment variable

Resource Limitation

Linux provides settings to limit system resources such as CPU, memory, and files. Proper configuration is necessary because the purpose of preventing a specific user from monopolizing system resources, or the limitation of file creation or memory allocation, has a fatal effect on the operation of the Altibase server.

The resource items and recommended values in the Altibase server operating environment are as follows.

Related Error Message

This is an error message caused by resource limitations. If the following message is checked while operating the Altibase server, it is necessary to check the resource limit settings.

• Insufficient max user processes

  • Failed to create a thread object.

  • resource temporarily unavailable

• Insufficient open files

  • Too many open files

View and Change Resource Settings

Resource limits are set for each user, but apply individually to user processes.

To reflect the changed resource limit settings to the Altibase server, the Altibase server must be restarted.

How to Check Set Value

This command checks the resource limit setting value.

If the desired settings are not applied to the Altibase server process, the Altibase server must be restarted.

How to Change the Settings

Execute ulimit command

ulimit is a command to set resource limits. The ulimit configuration command is added to the .bash_profile of the configuration file of the OS user who installs and runs the Altibase server.

User resource limit setting example - added to .bash_profile

Apply the configuration file (.bash_profile)

Apply ulimit setting with the following command.

When applying the configuration file, the following error may occur.

This is an error caused by Hard-Limit.

Hard-Limit & Soft-Limit

System resource limits include Hard-Limit and Soft-Limit. Hard-Limit means the maximum resource limit setting value that can be set by the OS general user, and Soft-Limit means the resource limit value set by the user.

If Hard-Limit is smaller than the value that user wants to set as ulimit, 'cannot modify limit' error occurs.

How to check Hard-Limit

Change /etc/security/limits.conf

Hard-Limit changes require root privileges. Add the following setting to the limits.conf file and save it.

Hard-Limit configuration example - OS user name is altibase

Log in as the OS user and perform step 2 again.

Environment Variables

This is an environment variable to be set after installing the Altibase server.

• Environment variable MALLOC_ARENA_MAX

  • This environment variable is optional.

  • In general, consider keeping the default value and setting it smaller than the default value if a memory issue is found.

  • Since this environment variable affects the performance and memory usage of the Altibase server process according to the set value, it is difficult to recommend the same value collectively.

  • The default value of this environment variable is influenced by the number of CPU cores. As the number of CPU cores increases, the VSZ of the Altibase server process may increase excessively.

How to Set Environment Variables

How to Check the Set Value

Check if the required environment variables are set correctly.

env command

The env result prints all environment variables set for the session.

echo command

The specified environment variable settings are output. If the value is not output, it means that the environment variable is not set.

How to Change the Settings

This is a method of setting the ALTIBASE_NLS_USE and LANG environment variables that must be manually set among the required environment variables.

Check the Altibase server character set

Set environment variables in .bash_profile file

Environment variables are set in units of OS user sessions. Therefore, it must be added to the user configuration file .bash_profile to be applied every time an OS user connects.

The table below shows the ALTIBASE_NLS_USE and LANG environment variable settings according to the Altibase server character set.

Refer to the table above and add environment variables to the user configuration file .bash_profile.

Environment variable setting example - added to .bash_profile

Apply to the configuration file .bash_profile

Apply the environment variable added with the following command.

Summary

Others

Red Hat Enterprise Linux Recommended Swap Size

Red Hat Linux recommends the following for Swap sizing.

• In the past, twice as much swap space as physical memory was recommended, but today with terabytes of memory, the last recommendation is not practical.

• For systems with more than 140 logical processors or systems with more than 3 TB of RAM, a minimum swap space of 100 GB is recommended.

For details, refer to the Red Hat CUSTOMER PORTAL page.

 What is the recommended swap size for Red Hat platforms?

Force termination of Altibase server process by timeout setting when registering Altibase startup service with systemd

Note for Linux distributions using RHEL 7 or higher or systemd.

If there is a timeout setting in the systemd service configuration file, there may be a phenomenon in which the Altibase server process is forcibly terminated by the OS while the Altibase server process is running during the OS boot process.

• TimeoutStartSec or TimeoutSec
  
  In this case, the following message is left in the system log (messages).

• Memory data and memory index is large or 
•  When Restart Recovery is in progress while Altibase is running

TimeoutStartSec or TimeoutSec setting value must be set enough according to the operating environment or set to 0 (timeout disabled).

 Similarly, there is a TimeoutStopSec setting. 

 Please refer to 'man systemd.service' for more details.