Updated on 2023-03-15 GMT+08:00

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. Services are not interrupted during cluster scale-in.

Prerequisites

The target cluster is available and has no tasks in progress.

Constraints

  • The node specifications and storage capacity cannot be modified during scale-in.
  • If you change the number and storage capacity of a specified type of node, nodes in other types will not be changed.
  • Ensure that the disk usage after scale-in is less than 80% and each AZ of each node type has at least one node.
  • When scaling in a cluster, the data in the node to be deleted is migrated to other nodes. The timeout threshold for data migration is five hours. If data migration is not complete within 5 hours, the cluster scale-in fails. You are advised to perform scale-in for multiple times when the cluster has huge amounts of data.
  • For a cluster without master nodes, the number of remaining data nodes (including cold data nodes and other types of nodes) after scale-in must be greater than half of the original node number, and greater than the maximum number of index replicas.
  • The quota of nodes in different types varies. For details, see Table 1.
    Table 1 Number of nodes in different types

    Node Type

    Number

    ess

    ess: 1-32

    ess, ess-master

    ess: 1-200

    ess-master: an odd number ranging from 3 to 9

    ess, ess-client

    ess: 1-32

    ess-client: 1-32

    ess, ess-cold

    ess: 1-32

    ess-cold: 1-32

    ess, ess-master, ess-client

    ess: 1-200

    ess-master: an odd number ranging from 3 to 9

    ess-client: 1-32

    ess, ess-master, ess-cold

    ess: 1-200

    ess-master: an odd number ranging from 3 to 9

    ess-cold: 1-32

    ess, ess-client, ess-cold

    ess: 1-32

    ess-client: 1-32

    ess-cold: 1-32

    ess, ess-master, ess-client, ess-cold

    ess: 1-200

    ess-master: an odd number ranging from 3 to 9

    ess-client: 1-32

    ess-cold: 1-32

    Details about the four node types:
    • ess: the default node type that is mandatory for cluster creation. The other three node types are optional.
    • ess-master: master node
    • ess-client: client node
    • ess-cold: cold data node

Procedure

  1. Log in to the CSS management console.
  2. In the navigation pane on the left, choose Clusters > Elasticsearch. On the displayed Clusters page, locate the target cluster and choose More > Modify Configuration in the Operation column.
  3. On the Modify Configuration page, choose the Scale Cluster tab and click Scale in to set parameters.
    • Action: Select Scale in.
    • New Nodes: The number of default nodes. For details about the quota, see Table 1.
    • If a cluster has master nodes, client nodes, or cold data nodes, you can change the node number. For details about the quotas of the master, client, and cold data node, see Table 1.
  4. Click Next: Scale Now.
  5. Confirm the information and click Submit.
  6. Click Back to Cluster List to switch to the Clusters page. The Task Status is Scaling in. When Cluster Status changes to Available, the cluster has been successfully scaled in.