IMPORTANT: No additional bug fixes or documentation updates will be released for this version. For the latest information, see the current release documentation.

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Advanced configuration

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Advanced configuration

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Modifying advanced settings is generally not recommended and could negatively impact performance and stability. Using the Elasticsearch-provided defaults is recommended in most circumstances.

Set JVM options

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If needed, you can override the default JVM options by adding custom options files (preferred) or setting the ES_JAVA_OPTS environment variable.

JVM options files must have the suffix .options and contain a line-delimited list of JVM arguments. JVM processes options files in lexicographic order.

Where you put the JVM options files depends on the type of installation:

tar.gz or .zip: Add custom JVM options files to config/jvm.options.d/.
Debian or RPM: Add custom JVM options files to /etc/elasticsearch/jvm.options.d/.
Docker: Bind mount custom JVM options files into /usr/share/elasticsearch/config/jvm.options.d/.

Do not modify the root jvm.options file. Use files in jvm.options.d/ instead.

JVM options syntax

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A JVM options file contains a line-delimited list of JVM arguments. Arguments are preceded by a dash (-). To apply the setting to specific versions, prepend the version or a range of versions followed by a colon.

Apply a setting to all versions:
```
-Xmx2g
```
Apply a setting to a specific version:
```
8:-Xmx2g
```
Apply a setting to a range of versions:
```
8-9:-Xmx2g
```
To apply a setting to a specific version and any later versions, omit the upper bound of the range. For example, this setting applies to Java 8 and later:
```
8-:-Xmx2g
```

Blank lines are ignored. Lines beginning with # are treated as comments and ignored. Lines that aren’t commented out and aren’t recognized as valid JVM arguments are rejected and Elasticsearch will fail to start.

Use environment variables to set JVM options

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In production, use JVM options files to override the default settings. In testing and development environments, you can also set JVM options through the ES_JAVA_OPTS environment variable.

export ES_JAVA_OPTS="$ES_JAVA_OPTS -Djava.io.tmpdir=/path/to/temp/dir"
./bin/elasticsearch

If you’re using the RPM or Debian packages, you can specify ES_JAVA_OPTS in the system configuration file.

Elasticsearch ignores the JAVA_TOOL_OPTIONS and JAVA_OPTS environment variables.

Set the JVM heap size

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By default, Elasticsearch automatically sets the JVM heap size based on a node’s roles and total memory. Using the default sizing is recommended for most production environments.

Automatic heap sizing requires the bundled JDK or, if using a custom JRE location, a Java 14 or later JRE.

To override the default heap size, set the minimum and maximum heap size settings, Xms and Xmx. The minimum and maximum values must be the same.

The heap size should be based on the available RAM:

Set Xms and Xmx to no more than 50% of your total memory. Elasticsearch requires memory for purposes other than the JVM heap. For example, Elasticsearch uses off-heap buffers for efficient network communication and relies on the operating system’s filesystem cache for efficient access to files. The JVM itself also requires some memory. It’s normal for Elasticsearch to use more memory than the limit configured with the Xmx setting.

When running in a container, such as Docker, total memory is defined as the amount of memory visible to the container, not the total system memory on the host.
Set Xms and Xmx to no more than 32 GB, the approximate threshold for compressed ordinary object pointers (oops). To verify you are under the threshold, check elasticsearch.logs for an entry like this:
```
heap size [1.9gb], compressed ordinary object pointers [true]
```
Set Xms and Xmx to no more than the threshold for zero-based compressed oops. The exact threshold varies but 26GB is safe on most systems and can be as large as 30GB on some systems. You can verify that you are under this threshold by starting Elasticsearch with the JVM options -XX:+UnlockDiagnosticVMOptions -XX:+PrintCompressedOopsMode and checking elasticsearch.logs for an entry like this:
```
heap address: 0x000000011be00000, size: 27648 MB, zero based Compressed Oops
```
This entry shows that zero-based compressed oops are enabled. If zero-based compressed oops are not enabled, the entry looks like this:
```
heap address: 0x0000000118400000, size: 28672 MB, Compressed Oops with base: 0x00000001183ff000
```

The more heap available to Elasticsearch, the more memory it can use for its internal caches. This leaves less memory for the operating system to use for the filesystem cache. Larger heaps can also cause longer garbage collection pauses.

To configure the heap size, add the Xms and Xmx JVM arguments to a custom JVM options file with the extension .options and store it in the jvm.options.d/ directory. For example, to set the maximum heap size to 2GB, set both Xms and Xmx to 2g:

-Xms2g
-Xmx2g

For testing, you can also set the heap sizes using the ES_JAVA_OPTS environment variable:

ES_JAVA_OPTS="-Xms2g -Xmx2g" ./bin/elasticsearch

The ES_JAVA_OPTS variable overrides all other JVM options. We do not recommend using ES_JAVA_OPTS in production.

If you are running Elasticsearch as a Windows service, you can change the heap size using the service manager. See Installing Elasticsearch as a Service on Windows.

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