Elasticsearch Nodes

By Opster Team

Updated: Jan 28, 2024

| 1 min read


To put it simply, a node is a single server that is part of a cluster. Each node is assigned one or more roles, which describe the node’s responsibility and operations. Data nodes store the data, and participate in the cluster’s indexing and search capabilities, while master nodes are responsible for managing the cluster’s activities and storing the cluster state, including the metadata.

While it is possible to run several node instances of Elasticsearch on the same hardware, it’s considered a best practice to limit a server to a single running instance of Elasticsearch.

Nodes connect to each other and form a cluster by using a discovery method. 


Master node

Master nodes are in charge of cluster-wide settings and changes – deleting or creating indices and fields, adding or removing nodes and allocating shards to nodes. Each cluster has a single master node that is elected from the master eligible nodes using a distributed consensus algorithm and is reelected if the current master node fails.

Coordinating (client) node

There is some confusion in the use of coordinating node terminology. Client nodes were removed from Elasticsearch after version 2.4 and became coordinating nodes.

Coordinating nodes are nodes that do not hold any configured role. They don’t hold data and are not part of the master eligible group nor execute ingest pipelines. Coordinating nodes serve incoming search requests and act as the query coordinator running query and fetch phases, sending requests to every node that holds a shard being queried. The coordinating node also distributes bulk indexing operations and route queries to shards based on the node’s responsiveness.

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Related log errors to this ES concept

Node closed while execution action for shard entry
Failed to send response
JVM arguments
Timed out while waiting for initial discovery state - timeout
Connection failed to node at
Successfully completed and scheduled task in node operation
NodeStatsAction timed out for ClusterInfoUpdateJob
Failed to execute NodeStatsAction for ClusterInfoUpdateJob
Failed to update node information for ClusterInfoUpdateJob within timeout
Unable to retrieve node FS stats for
Failed to disconnect to node
Flood stage disk watermark exceeded on all indices on this node will be marked read-only

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