I don't mean to be cavalier about misconfiguration, but it's not like the retention period is the Sword of Damocles. It's a configuration setting, and Kafka honors it reliably. As other commenters have pointed out, there are other bad things you can do to cause data loss with any system no matter how hard you try. These stories will continue to grace post-mortem blog posts long after we are gone, but stories of Kafka accidentally not retaining data do not seem to be thick on the ground. Any non-trivial system has its rough edges, but this just doesn't seem to be one of them for Kafka.