CassandraConnectionTimeoutsTotal #

Some connection between nodes are ending in timeout - {{ $labels.cassandra_cluster }}

alert: CassandraConnectionTimeoutsTotal
annotations:
  description: |-
    Some connection between nodes are ending in timeout - {{ $labels.cassandra_cluster }}
      VALUE = {{ $value }}
      LABELS = {{ $labels }}    
  runbook: https://srerun.github.io/prometheus-alerts/runbooks/instaclustr-cassandra-exporter/cassandraconnectiontimeoutstotal/
  summary: Cassandra connection timeouts total (instance {{ $labels.instance }})
expr: avg(cassandra_client_request_timeouts_total) by (cassandra_cluster,instance)
  > 5
for: 2m
labels:
  severity: critical

Here is a runbook for the CassandraConnectionTimeoutsTotal alert:

Meaning #

The CassandraConnectionTimeoutsTotal alert indicates that there are an excessive number of timeouts when connecting to a Cassandra cluster. This can lead to failed requests, data inconsistencies, and overall degraded system performance.

Impact #

• Failed requests and errors will be returned to clients, leading to a poor user experience.
• Data inconsistencies may arise due to incomplete writes or reads.
• System performance will degrade, leading to slower response times and potential cascading failures.
• In extreme cases, the Cassandra cluster may become unavailable, leading to complete system downtime.

Diagnosis #

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

1. Check the Cassandra cluster logs for errors or warnings related to connection timeouts.
2. Verify that the Cassandra nodes are properly configured and correctly connected to each other.
3. Check the network connectivity between the nodes to ensure there are no issues with packet loss, latency, or network Interface errors.
4. Review the Cassandra configuration to ensure that the timeout settings are properly set and not too aggressive.
5. Check the system resources (CPU, memory, disk) to ensure that they are not under-provisioned or experiencing high utilization.

Mitigation #

To mitigate the CassandraConnectionTimeoutsTotal alert, follow these steps:

1. Increase the timeout settings in the Cassandra configuration to allow for more time to establish connections.
2. Investigate and resolve any network connectivity issues between nodes.
3. Verify that the Cassandra nodes are properly configured and correctly connected to each other.
4. Consider increasing system resources (CPU, memory, disk) to reduce contention and improve overall system performance.
5. Consider implementing connection pooling or other optimization techniques to reduce the load on the Cassandra cluster.

Remember to update the cassandra_client_request_timeouts_total metric to reflect the changes made, and to continue monitoring the alert to ensure that the mitigation steps have been effective.