Add Reserve Node

This section describes how to define an existing node as a reserve node.

Reserve nodes are standby nodes that will take over if an active node in the cluster fails. For more information about the failover mechanisms in Exasol, see Fail Safety.

Prerequisites

The node to be defined as a reserve node must already be added to the cluster and configured accordingly.

Procedure

This procedure is carried out using ConfD.

The ConfD examples are written in Bash on a Linux terminal running the Exasol tool confd_client, which is accessed by connecting to EXAClusterOS on the database nodes using Exasol Deployment Tool (c4). You can also interact with ConfD from an external tool using Python and XML-RPC. For more information, see ConfD.

Placeholder values are indicated with UPPERCASE characters. Replace the placeholders with your own values.

  1. Stop the database. For more information, see Stop a Database.

  2. To add one or more nodes as reserve nodes, use the ConfD job db_add_reserve_nodes. For example: 

    confd_client -c db_add_reserve_nodes -a '{"db_name": "MY_DATABASE", "node_list": [16, 17]}'

Verification

To verify that the reserve nodes have been added, use the ConfD job node_list. 

confd_client -c node_list