Overview

You can scale in or out a cluster and change cluster specifications. In this way, you can improve cluster efficiency and reduce O&M costs.

Scaling Out a Cluster

If a data node (ess) processes many data writing and querying requests and responds slowly, you can expand its storage capacity to improve its efficiency. If some nodes turn unavailable due to the excessive data volume or misoperations, you can add new nodes to ensure the cluster availability.
Cold data nodes (ess-cold) are used to share the workload of data nodes. To prevent cold data loss, you can expand the storage capacity of the cold data node or add new ones.

Changing Specifications

If the allocation of new indexes or shards takes too long or the node coordination and scheduling are inefficient, you can change the master node (ess-master) specifications.
If too many tasks need to be distributed or too many results have been aggregated, you can change the client node (ess-client) specifications.
If the speed of data writing and query decreases suddenly, you can change the data node (ess) specifications.
If cold data query becomes slow, you can change the cold node (ess-cold) specifications.

Scaling in a Cluster

If a cluster can process existing data without fully using its resources, you can scale in the cluster to reduce costs.

Removing Specified Nodes

If a cluster can process existing data without fully using its nodes, you can remove one or more specified nodes from the cluster to reduce costs.

Replacing a Specified Node

If a node in the cluster is faulty, you can create a new node with the same specifications to replace it.

Adding Master/Client Nodes

If the workloads on the data plane of a cluster increase, you can dynamically scale the cluster by adding master/client nodes.

After a cluster is created, its security mode can be changed using the following methods:

Change a non-security cluster to a security cluster that uses HTTP or HTTPS protocol.
Change a security cluster that uses HTTP or HTTPS protocol to a non-security cluster.
Change the protocol of a security cluster.

Parent topic: Changing the Elasticsearch Cluster Form