[role="xpack"]
[[xpack-autoscaling]]
= Autoscaling

NOTE: {cloud-only}

The autoscaling feature enables an operator to configure tiers of nodes that
self-monitor whether or not they need to scale based on an operator-defined
policy. Then, via the autoscaling API, an Elasticsearch cluster can report
whether or not it needs additional resources to meet the policy. For example, an
operator could define a policy that a warm tier should scale on available disk
space. Elasticsearch would monitor and forecast the available disk space in the
warm tier, and if the forecast is such that the cluster will soon not be able to
allocate existing and future shard copies due to disk space, then the
autoscaling API would report that the cluster needs to scale due to disk space.
It remains the responsibility of the operator to add the additional resources
that the cluster signals it requires.

A policy is composed of a list of roles and a list of deciders. Nodes matching
the roles are governed by the policy. The deciders provide independent estimates
of the capacity required. See <<autoscaling-deciders,Autoscaling deciders>> for
more information on the deciders available.

Autoscaling supports the scale-up and scale-down of dedicated {ml}
nodes. Autoscaling also supports the scale-up of data nodes based on storage.
[NOTE]
Autoscaling is not supported on Debian 8.

include::autoscaling-deciders.asciidoc[]
