CassandraClientRequestWriteFailure

CassandraClientRequestWriteFailure #

Read failures have occurred, ensure there are not too many unavailable nodes - {{ $labels.cassandra_cluster }}

Alert Rule
alert: CassandraClientRequestWriteFailure
annotations:
  description: |-
    Read failures have occurred, ensure there are not too many unavailable nodes - {{ $labels.cassandra_cluster }}
      VALUE = {{ $value }}
      LABELS = {{ $labels }}    
  runbook: https://srerun.github.io/prometheus-alerts/runbooks/instaclustr-cassandra-exporter/cassandraclientrequestwritefailure/
  summary: Cassandra client request write failure (instance {{ $labels.instance }})
expr: increase(cassandra_client_request_failures_total{operation="write"}[1m]) > 0
for: 2m
labels:
  severity: critical

Here is a runbook for the Prometheus alert rule CassandraClientRequestWriteFailure:

Meaning #

This alert is triggered when there is an increase in write request failures to a Cassandra cluster within a 1-minute window. This indicates that the Cassandra client is experiencing issues writing data to the cluster, which can lead to data loss or inconsistencies.

Impact #

The impact of this alert varies depending on the nature of the application and the data being written. In general, this alert can cause:

  • Data loss or corruption
  • Inconsistent data across replicas
  • Increased latency or timeouts for write operations
  • Potential cascading failures in dependent systems

Diagnosis #

To diagnose the root cause of this alert, follow these steps:

  1. Check the Cassandra cluster health:
    • Verify that there are no unavailable nodes in the cluster.
    • Check the node status and ensure that all nodes are online and reachable.
  2. Investigate the Cassandra client logs:
    • Check the client logs for any error messages related to write requests.
    • Verify that the client is correctly configured and authenticated to the Cassandra cluster.
  3. Check the Cassandra cluster configuration:
    • Verify that the cluster is properly configured for writes (e.g., correct replication factor, consistent hashing, etc.).
  4. Check for network issues:
    • Verify that there are no network connectivity issues between the client and the Cassandra cluster.

Mitigation #

To mitigate this alert, follow these steps:

  1. Identify and resolve any unavailable nodes in the Cassandra cluster:
    • Investigate the node status and identify the cause of any node unavailability.
    • Perform any necessary repairs or replacements to bring the node back online.
  2. Verify and correct Cassandra client configuration:
    • Check the client configuration for any errors or misconfigurations.
    • Ensure that the client is correctly authenticated and authorized to write to the Cassandra cluster.
  3. Verify and correct Cassandra cluster configuration:
    • Check the cluster configuration for any errors or misconfigurations.
    • Ensure that the cluster is properly configured for writes (e.g., correct replication factor, consistent hashing, etc.).
  4. Implement retry mechanisms:
    • Consider implementing retry mechanisms in the Cassandra client to handle temporary write failures.
  5. Monitor and analyze write request patterns:
    • Analyze write request patterns to identify any trends or anomalies that may indicate a larger issue.

Remember to consult the Cassandra cluster and client documentation for specific troubleshooting and configuration guidance.

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