Elasticsearch Node



Elasticsearch Node

Opster Team

July 2020, Version: 1.7-8.0


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Nodes in Elasticsearch

What it is

Simply explained a node is a single server that is part of a cluster. Each node is assigned with one or more roles, which describes the node responsibility and operations – Data nodes stores the data, and participates in the cluster’s indexing and search capabilities, while master nodes are responsible for managing the cluster activities and storing the cluster state, including the metadata.

While it’s 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. 

Roles
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.

Coordinator Node (aka client node)

Coordinator Node – is a node that does not hold any configured role. It doesn’t hold data, not part of the master eligible group nor execute ingest pipelines. Coordinator node serves incoming search requests and is acting as the query coordinator – running the query and fetch phases, sending requests to every node which holds a shard being queried. The client node also distributes bulk indexing operations and route queries to shards copies based on the nodes responsiveness.


Related log errors to this ES concept


Failed to close node
Failed to close node on failed start
Removing node
failed to list shard for on node
Failed to verify repository
Job update was submitted to non-master node
Failed to disconnect to node
Failed to execute NodeStatsAction for ClusterInfoUpdateJob
Failed to update node information for ClusterInfoUpdateJob within timeout
Timed out while waiting for initial discovery state timeout:
Unable to retrieve node FS stats for (version 6.8)
Failed to validate incoming join request from node

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