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Checking the node status

Updated on May 17, 2024

This content applies only to On-premises and Client-managed cloud environments

Check the status of Decision Data Store (DDS) nodes, for example, to troubleshoot Cassandra-related failures listed in Pega logs.

  1. If you are using Cassandra in embedded mode, perform the following steps:
    Note:

    Starting in Pega Platform version 8.6, the use of an internal Cassandra database is deprecated. On-premises and client-managed cloud systems that have been updated from earlier versions of Pega Platform can continue to use Cassandra in embedded mode. However, to ensure future compatibility, do not create any new environments using embedded Cassandra.

    1. In the header of Dev Studio, click ConfigureDecisioningInfrastructureServicesDecision Data Store.
    2. On the Decision Data Store landing page, ensure that data correctly replicates across nodes by verifying that the ownership percentages of all DDS nodes add up to 100%.
      Tip: To check the ownership percentage for a selected node, click the status of the node, and then examine the Owns section.
  2. For both external and embedded Cassandra, check the node state in the nodetool utility:
    1. In the nodetool utility, run the nodetool status command.
      Result: Nodetool returns a cluster status report, as in the following example: 
      Datacenter: datacenter1
=======================
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
--  Address     Load       Tokens  Owns (effective)  Host ID                               Rack
UN  10.0.52.7   229.36 KB  256     100.0%            69d1a4da-fe18-483f-9ff8-5ffa8af94eca  rack1
UN  10.0.52.9   125.13 KB  256     100.0%            1fc331b1-47af-4760-973d-a34903fb0235  rack1
UN  10.0.52.11  103.92 KB  256     100.0%            2ddffb1d-1bf1-4b20-9da9-a305f325826e  rack1
      Note: The ownership percentages in the nodetool report are different than the percentages shown on the DDS landing page. The nodetool report describes both original data and replicated data, whereas the DDS landing page only refers to original data. For example, for a three-node cluster with a replication factor of 3, the nodetool report returns a 100% ownership for each node; for a four-node cluster with a replication factor of 3, the nodetool report returns a 75% ownership for each node, and so on.
    2. Ensure that the cluster status report lists all nodes.
    3. In the -- column, ensure that all nodes are marked as UN.
      UN means that the node status is UP and that the node state is NORMAL.
  3. If a node does not have UN status, investigate the source of the problem, for example, by performing other Cassandra troubleshooting procedures.
    For more information, see the Troubleshooting section of the Apache Cassandra documentation.

Related articles

Recovering a node (deprecated)Pega alerts for Cassandra

Tags

Pega Platform 8.6 Decision Management

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