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Unable to add a node to the Decision Data Store service

This issue might occur on Pega® Platform servers that run Microsoft Windows as their operating system. When adding a node to the Decision Data Store service, the JOIN_FAILED status message is displayed and the Pega Platform logs display a message that is similar to the following message:

<code class="language-java">java.lang.RuntimeException: java.util.concurrent.ExecutionException: com.pega.pegarules.pub.PRRuntimeException: Cannot bootstrap cassandra
at com.google.common.base.Throwables.propagate(Throwables.java:160)
at com.pega.dsm.dnode.impl.stream.DataObservableImpl.await(DataObservableImpl.java:124)
at com.pega.dsm.dnode.impl.stream.DataObservableImpl.await(DataObservableImpl.java:88)
at com.pegarules.generated.activity.ra_action_pzasyncexecuteoperation_f8bc98ec5361bd113e14e2f210cd31d0.step1_circum0(ra_action_pzasyncexecuteoperation_f8bc98ec5361bd113e14e2f210cd31d0.java:160)
at com.pegarules.generated.activity.ra_action_pzasyncexecuteoperation_f8bc98ec5361bd113e14e2f210cd31d0.perform(ra_action_pzasyncexecuteoperation_f8bc98ec5361bd113e14e2f210cd31d0

Caused by: com.pega.dsm.dnode.api.DNodeException: Unable to start DDS. Process has exited with code: 0
WARNING! Powershell script execution unavailable.
Please use 'powershell Set-ExecutionPolicy Unrestricted'
on this user-account to run cassandra with fully featured
functionality on this platform.
Starting with legacy startup options
Starting Cassandra Server</code>

Cause

When you add a node to the Decision Data Store service, Pega Platform deploys an Apache Cassandra database on that node. For nodes running the Windows operating system, Cassandra requires that the script execution policy be set to Unrestricted, which permits loading all files and running all scripts. If the execution policy is set to any other level while a node is added to the Decision Data Store, that node is not added to the service and the JOIN_FAILED message is displayed.

Solution

To eliminate this error, change the user preferences for the Windows PowerShell execution policy, remove the failed node from the service, and then add that node back.

  1. In the PowerShell console of the failed node, enter the following command:

    Set-ExecutionPolicy Unrestricted

  2. Remove the failed node from the Decision Data Store service:
    1. Click Designer Studio > Decisioning > Infrastructure > Services > Decision Data Store.
    2. In the Decision data store nodes section, locate the node that did not join the service as a result of an incorrect execution policy level.
    3. In the Action column for that node, click Execute > Decommission.
  3. Add the node back to the Decision Data Store service:
    1. In the Decision data store section, click Add node.
    2. Select the node that you just decommissioned.
    3. Click Submit.
    4. Click Refresh until the status of the node changes from JOINING to NORMAL.

Published May 23, 2017 — Updated June 2, 2017


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