
[role="xpack"]
[[ml-settings]]
=== Machine learning settings in Elasticsearch
++++
<titleabbrev>Machine learning settings</titleabbrev>
++++

You do not need to configure any settings to use {ml}. It is enabled by default.

IMPORTANT: {ml-cap} uses SSE4.2 instructions, so will only work on machines whose
CPUs https://en.wikipedia.org/wiki/SSE4#Supporting_CPUs[support] SSE4.2. If you
run {es} on older hardware you must disable {ml} (by setting `xpack.ml.enabled`
to `false`).

All of these settings can be added to the `elasticsearch.yml` configuration file. 
The dynamic settings can also be updated across a cluster with the 
<<cluster-update-settings,cluster update settings API>>.

TIP: Dynamic settings take precedence over settings in the `elasticsearch.yml` 
file.

[float]
[[general-ml-settings]]
==== General machine learning settings

`node.ml`::
Set to `true` (default) to identify the node as a _machine learning node_. +
+
If set to `false` in `elasticsearch.yml`, the node cannot run jobs. If set to
`true` but `xpack.ml.enabled` is set to `false`, the `node.ml` setting is
ignored and the node cannot run jobs. If you want to run jobs, there must be at
least one machine learning node in your cluster. +
+
IMPORTANT: On dedicated coordinating nodes or dedicated master nodes, disable
the `node.ml` role.

`xpack.ml.enabled`::
Set to `true` (default) to enable {ml} on the node. +
+
If set to `false` in `elasticsearch.yml`, the {ml} APIs are disabled on the node.
Therefore the node cannot open jobs, start {dfeeds}, or receive transport (internal)
communication requests related to {ml} APIs. It also affects all {kib} instances
that connect to this {es} instance; you do not need to disable {ml} in those
`kibana.yml` files. For more information about disabling {ml} in specific {kib}
instances, see
{kibana-ref}/ml-settings-kb.html[{kib} Machine Learning Settings].
+
IMPORTANT: If you want to use {ml} features in your cluster, you must have
`xpack.ml.enabled` set to `true` on all master-eligible nodes. This is the
default behavior.

`xpack.ml.max_machine_memory_percent` (<<cluster-update-settings,Dynamic>>)::
The maximum percentage of the machine's memory that {ml} may use for running
analytics processes. (These processes are separate to the {es} JVM.) Defaults to
`30` percent. The limit is based on the total memory of the machine, not current
free memory. Jobs will not be allocated to a node if doing so would cause the
estimated memory use of {ml} jobs to exceed the limit.

`xpack.ml.max_model_memory_limit` (<<cluster-update-settings,Dynamic>>)::
The maximum `model_memory_limit` property value that can be set for any job on
this node. If you try to create a job with a `model_memory_limit` property value
that is greater than this setting value, an error occurs. Existing jobs are not
affected when you update this setting. For more information about the
`model_memory_limit` property, see <<ml-apilimits>>.

`xpack.ml.max_open_jobs` (<<cluster-update-settings,Dynamic>>)::
The maximum number of jobs that can run simultaneously on a node. Defaults to
`20`. In this context, jobs include both anomaly detector jobs and data frame
analytics jobs. The maximum number of jobs is also constrained by memory usage.
Thus if the estimated memory usage of the jobs would be higher than allowed,
fewer jobs will run on a node. Prior to version 7.1, this setting was a per-node
non-dynamic setting. It became a cluster-wide dynamic
setting in version 7.1. As a result, changes to its value after node startup
are used only after every node in the cluster is running version 7.1 or higher.
The maximum permitted value is `512`.

`xpack.ml.node_concurrent_job_allocations` (<<cluster-update-settings,Dynamic>>)::
The maximum number of jobs that can concurrently be in the `opening` state on
each node. Typically, jobs spend a small amount of time in this state before
they move to `open` state. Jobs that must restore large models when they are
opening spend more time in the `opening` state. Defaults to `2`.

[float]
[[advanced-ml-settings]]
==== Advanced machine learning settings

These settings are for advanced use cases; the default values are generally 
sufficient:

`xpack.ml.enable_config_migration` (<<cluster-update-settings,Dynamic>>)::
Reserved.

`xpack.ml.max_anomaly_records` (<<cluster-update-settings,Dynamic>>)::
The maximum number of records that are output per bucket. The default value is 
`500`.

`xpack.ml.max_lazy_ml_nodes` (<<cluster-update-settings,Dynamic>>)::
The number of lazily spun up Machine Learning nodes. Useful in situations
where ML nodes are not desired until the first Machine Learning Job
is opened. It defaults to `0` and has a maximum acceptable value of `3`.
If the current number of ML nodes is `>=` than this setting, then it is
assumed that there are no more lazy nodes available as the desired number
of nodes have already been provisioned. When a job is opened with this
setting set at `>0` and there are no nodes that can accept the job, then
the job will stay in the `OPENING` state until a new ML node is added to the
cluster and the job is assigned to run on that node.
+
IMPORTANT: This setting assumes some external process is capable of adding ML nodes
to the cluster. This setting is only useful when used in conjunction with
such an external process.

`xpack.ml.process_connect_timeout` (<<cluster-update-settings,Dynamic>>)::
The connection timeout for {ml} processes that run separately from the {es} JVM.
Defaults to `10s`. Some {ml} processing is done by processes that run separately
to the {es} JVM. When such processes are started they must connect to the {es}
JVM. If such a process does not connect within the time period specified by this
setting then the process is assumed to have failed. Defaults to `10s`. The minimum
value for this setting is `5s`.
