// Module included in the following assemblies:
//
// * architecture/control-plane.adoc


:_mod-docs-content-type: CONCEPT
[id="etcd-overview_{context}"]
= Overview of etcd

etcd is a consistent, distributed key-value store that holds small amounts of data that can fit entirely in memory. Although etcd is a core component of many projects, it is the primary data store for Kubernetes, which is the standard system for container orchestration.

[id="etcd-benefits_{context}"]
== Benefits of using etcd

By using etcd, you can benefit in several ways:

* Maintain consistent uptime for your cloud-native applications, and keep them working even if individual servers fail
* Store and replicate all cluster states for Kubernetes
* Distribute configuration data to provide redundancy and resiliency for the configuration of nodes

[id="etcd-architecture_{context}"]
== How etcd works

To ensure a reliable approach to cluster configuration and management, etcd uses the etcd Operator. The Operator simplifies the use of etcd on a Kubernetes container platform like {product-title}. With the etcd Operator, you can create or delete etcd members, resize clusters, perform backups, and upgrade etcd.

The etcd Operator observes, analyzes, and acts:

. It observes the cluster state by using the Kubernetes API.
. It analyzes differences between the current state and the state that you want.
. It fixes the differences through the etcd cluster management APIs, the Kubernetes API, or both.

etcd holds the cluster state, which is constantly updated. This state is continuously persisted, which leads to a high number of small changes at high frequency.
ifndef::openshift-dedicated,openshift-rosa[]
As a result, it is critical to back the etcd cluster member with fast, low-latency I/O. For more information about best practices for etcd, see "Recommended etcd practices".
endif::openshift-dedicated,openshift-rosa[]
ifdef::openshift-dedicated,openshift-rosa[]
As a result, Red Hat Site Reliability Engineering (SRE) backs the etcd cluster member with fast, low-latency I/O.
endif::openshift-dedicated,openshift-rosa[]
