Addressing common issues Learn about the most commonly encountered Cassandra issues and how to address them. Input/output blockages in the Cassandra cluster Address input/output (I/O) blockages in a Cassandra cluster or low CPU resources by reviewing the CPU statistics. Increasingly slower read operations Read operations take a prolonged time, which impacts system performance. Unable to connect to Cassandra cluster A node cannot join the Decision Data Store (DDS) cluster. Unable to add a node to the Decision Data Store service When adding a node to the Decision Data Store service, the JOIN_FAILED status message displays. Authentication error in the Decision Data Store landing page If you do not specify user credentials for connecting to an external Cassandra database or if the credentials are incorrect, the Decision Data Store (DDS) landing page displays an authentication error. Cassandra user does not have the required permissions If Pega Platform tries to access an external Cassandra database through a Cassandra user that does not have the required permissions, the Decision Data Store (DDS) landing page displays an error. Cassandra error: Too many open files The Cassandra process might crash with an error that indicates that there are too many open files. By performing the following task, you can check for issues with querying, saving, or synchronizing data, and then correct the errors. Cassandra error: Too large commit log size Cassandra logs display the following error: java.lang.IllegalArgumentException: Mutation of number-value bytes is too large for the maximum size of number-value. Cassandra warning: Couldn't find cfId Cassandra logs display the Couldn't find cfId=column family ID warning. Clock skew across a Cassandra cluster Clock skew across a Cassandra cluster can cause synchronization and replication issues. Cassandra terminates on startup Linux terminates Cassandra on startup. Exit code 137 appears in the /etc/log/kern.log directory and in both Pega Platform Cassandra logs.