Help Center/ MapReduce Service/ User Guide/ Managing Clusters/ Logging In to a Cluster/ MRS Cluster Node Overview
Updated on 2024-04-11 GMT+08:00
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MRS Cluster Node Overview

An MRS cluster consists of multiple ECSs. The system manages nodes in node groups based on specifications. Nodes in the same node group use same ECS specifications. Nodes in a cluster can be classified into Master nodes, Core nodes, and Task nodes based on the roles of components deployed on the nodes. For details about the node types, see Table 1.

Table 1 Cluster node types

Node Type

Functions

Master node

Management node of an MRS cluster. It manages and monitors the cluster. In the navigation tree of the MRS management console, choose Clusters > Active Clusters, select a running cluster, and click its name to switch to the cluster details page. On the Nodes tab page, view the Name. The node that contains master1 in its name is the Master1 node. The node that contains master2 in its name is the Master2 node.

You can log in to a Master node either using VNC on the ECS management console or using SSH. After logging in to the Master node, you can access Core nodes without entering passwords.

The system automatically deploys the Master nodes in active/standby mode and supports the high availability (HA) feature for MRS cluster management. If the active management node fails, the standby management node switches to the active state and takes over services.

To determine whether the Master1 node is the active management node, see Determining Active and Standby Management Nodes.

Core node

Work node of an MRS cluster. It processes and analyzes data and stores process data.

In the Nodes tab of the cluster details page, the nodes in the node group whose Node Type includes Core are core nodes.

Task node

Compute node. When the compute resources of a cluster are insufficient, you can configure elastic scaling policies to increase nodes automatically.

In the Nodes tab of the cluster details page, the nodes in the node group whose Node Type is Task are task nodes.

If only the NodeManager (Yarn) or Supervisor (Storm) role is deployed in a node group in addition to basic mandatory roles, this node group is a Task node group.

MRS cluster nodes support remote login. The following remote login methods are available:

  • GUI login: Use the remote login function provided by the ECS management console to log in to the Linux interface of the Master node in the cluster.
  • SSH login: Applies to Linux ECSs only. You can use a remote login tool (such as PuTTY) to log in to an ECS. The ECS must have a bound EIP.

    For details about how to apply for and bind EIP for the Master node, see Assigning an EIP and Binding It to an ECS.

    You can log in to a Linux ECS using either a key pair or password.

    If you need to use a key pair to access a cluster node, you need to log in to the node as user root. For details, see Logging In to an ECS Using a Key Pair (SSH).

    For details about how to access a cluster node using a password, see Logging In to an ECS Using a Password (SSH).

Parent topic: Logging In to a Cluster