It is possible that if all the nodes fail at about the same time and after the broker acknowledged the message, then some messages will be lost because they were in memory and not yet fully written to the disk. If you set ACKS=all then this requires all of your replicas to fail in this way to lose a message which lowers the chances greatly but it will never be zero. Even
-----Original Message----- From: Toni Zehnder [mailto:toni.zehn...@namics.com.INVALID] Sent: Monday, September 24, 2018 9:25 AM To: users@kafka.apache.org Subject: [External] What happens if the complete Kafka Cluster crashes Hi there, What happens with the messages if a complete Kafka Cluster dies? Are they lost? Or writes Kafka the message to the hard disk so if the nodes gets started again they still have the messages? Best regards Toni This e-mail and any files transmitted with it are confidential, may contain sensitive information, and are intended solely for the use of the individual or entity to whom they are addressed. If you have received this e-mail in error, please notify the sender by reply e-mail immediately and destroy all copies of the e-mail and any attachments.