System settings configuration methods

This page describes where and how to apply operating system limits and environment variables for Elasticsearch, depending on your installation package and init system.

For which limits and values you must set (such as file descriptors, threads, memory lock, virtual memory, and so on), see Important system configuration and the pages linked from there.

Where to configure system settings depends on how Elasticsearch is installed and started, and which operating system you are using:

• When using the .zip or .tar.gz packages, Elasticsearch is typically started manually from a shell. In this case, system limits can be configured using /etc/security/limits.conf or by setting them directly in the shell using ulimit before starting Elasticsearch.

• When using .deb or .rpm packages, Elasticsearch runs as a system service managed by systemd. In this case, system limits must be configured in the service definition (for example, using LimitNOFILE in a systemd override file).

• Temporarily with ulimit.

• Permanently in /etc/security/limits.conf.

When using the RPM or Debian packages, most system settings are set in the system configuration file. However, systems which use systemd require that system limits are specified in a systemd configuration file.

On Linux systems, you can use ulimit to change resource limits on a temporary basis. Limits usually need to be set as root before switching to the user that will run Elasticsearch.

Common options for ulimit include:

• -n — maximum number of open file descriptors
• -u — maximum number of processes available to a single user
• -l — maximum size of memory that may be locked into RAM
• -a — show all current soft resource limits (use this to verify what is in effect)

For the full list of options, run help ulimit in Bash.

Use the option and value required for your setting (see the pages under Important system configuration). For example:

sudo su
ulimit -n 65535
ulimit -u 4096
su elasticsearch
		

1. Become root.
2. Set the open file descriptor limit for this session.
3. Set the maximum number of threads for this session.
4. Become the user that will run Elasticsearch (for example elasticsearch) before starting the process.

The new limit is only applied during the current session.

On Linux systems, persistent limits can be set for a particular user by editing the /etc/security/limits.conf file. Add lines for the elasticsearch user (or the account that runs Elasticsearch) with the limit type and value your deployment requires. The exact limit name depends on what you are configuring. For example, you can configure nofile (open files), nproc (processes), or memlock (locked memory). Replace <limit> and <value> accordingly:

elasticsearch  -  nofile  65535
		

This change will only take effect the next time the elasticsearch user opens a new session.

# session    required   pam_limits.so
		

When using the RPM or Debian packages, environment variables can be specified in the system configuration file, which is located in the relevant location for your package type:

However, system limits need to be specified via systemd.

Use the topic pages under Important system configuration to determine which environment variables or JVM options you need (for example ES_JAVA_OPTS, ES_TMPDIR, or paths set in jvm.options).

When using the RPM or Debian packages on systems that use systemd, system limits must be specified via systemd.

The systemd service file (/usr/lib/systemd/system/elasticsearch.service) contains the limits that are applied by default.

To override them, add a file called /etc/systemd/system/elasticsearch.service.d/override.conf (alternatively, you may run sudo systemctl edit elasticsearch which opens the file automatically inside your default editor). Set any changes in this file. For example, for resource limits and environment variables, include:

[Service]
LimitMEMLOCK=infinity
		

Replace the directives with those required for your deployment.

Once finished, run the following command to reload units:

sudo systemctl daemon-reload