A few strategies for migrating Kafka to new cluster from classic to VPC:
Launch a new cluster (Zookeeper+Kafka brokers),
point producers to new cluster and drain the older cluster once consumers are also pointed to new cluster.
- Existing cluster isn't impacted, and hence helps in easy revert.
- Smooth transition on kafka cluster end. No config changes or zookeeper changes.
- In case of revert, potential loss of messages.
- Consumers may have to take some downtime.
- Few consumers consume and produce to the cluster. They've to engineer to adapt both kafka clusters in their application.
Launch a new cluster (Zookeeper + Kafka brokers),
point producers to both the clusters. Let data in both clusters be eventually consistent. Once both the clusters are identical, drain the older cluster.
- Minimal engineering required is on producers (also, those who produce by consumption).
- Dummy consumers can be put up, and testing can be done somewhat smoothly.
- Potential risk of duplicate consumption of messages.
- Application need changes.
Add new brokers one by one, drain one by one.
Once the brokers are migrated, move zookeeper similarly.
- applications are agnostic to these changes. No engineering changes required.
- Draining a broker would turn out expensive. Cluster would take significant bandwidth and throttle upon network, causing distress to applications.
There's a way to put throttling limits on bandwidth and let migration happen in controlled manner.
- Operationally, lengthy procedure. Overall transition time would be in weeks.