The Resilient Mirror: Benchmarking Cross-Region Kafka Replication with AWS MSK Replicator vs. MirrorMaker 2

In the world of distributed systems, data locality is a luxury, but data resilience is a necessity. For CTOs and lead architects, the nightmare scenario isn't just a server failing—it's an entire AWS region going dark. Whether for Disaster Recovery (DR), data sovereignty compliance, or bringing data closer to users in different geographies, Cross-Region Replication (CRR) is the insurance policy you hope to never use but cannot afford to ignore.

For years, the gold standard for replicating Apache Kafka clusters has been MirrorMaker 2 (MM2). It is robust, open-source, and highly configurable. However, it also brings the "heavy lifting" of managing Kafka Connect clusters. Enter AWS MSK Replicator (often referred to as K2K), a fully managed feature of Amazon MSK that promises to turn cross-region replication into a serverless, point-and-click operation.

At Nohatek, we believe in making data-driven architectural decisions. We recently put both solutions to the test to answer the critical question: Is the convenience of the managed service worth the cost, or does the granular control of MirrorMaker 2 still reign supreme?

Round 1: Architecture and Operational Complexity

The fundamental difference between these two contenders lies in who carries the pager. To understand the benchmark results, we first need to look at what is actually being deployed.

MirrorMaker 2 (Self-Managed on EC2 or EKS)
MM2 runs on top of the Kafka Connect framework. To implement this, your team must provision compute resources (EC2 instances or Kubernetes pods), configure the connect-mirror-maker.properties, manage the JVM heap sizes, and handle auto-scaling based on throughput. While this offers infinite tweakability, it introduces significant operational overhead.

• Pros: Full control over batch sizes, compression types, and commit intervals. capable of running on Spot Instances to save costs.
• Cons: Requires deep expertise in Kafka Connect; you are responsible for patching, securing, and scaling the replication infrastructure.

AWS MSK Replicator (Serverless)
MSK Replicator abstracts the underlying Connect cluster entirely. You select your source cluster, your target cluster, and the IAM role. AWS handles the provisioning, scaling, and high availability of the replicator nodes.

The beauty of MSK Replicator is its integration with AWS IAM. Unlike MM2, which often requires complex SASL/SCRAM or mTLS management for cross-region auth, MSK Replicator leverages native AWS policies, significantly reducing the security surface area.

The Verdict on Complexity: MSK Replicator wins hands down for speed of deployment. We went from zero to replicating topics in under 15 minutes. MM2 required a day of Terraform scripting and configuration tuning to reach a stable baseline.

Round 2: The Benchmark (Latency and Throughput)

Convenience is nice, but performance is paramount. We set up a test scenario replicating data from us-east-1 (N. Virginia) to eu-west-1 (Ireland). This trans-Atlantic link introduces natural network latency, making it a perfect stress test for replication lag.

Test Parameters:

• Throughput: 50 MB/s constant load
• Message Size: 4KB
• Topic Configuration: replication.factor=3, min.insync.replicas=2

The Results:

1. Replication Latency:
Surprisingly, MirrorMaker 2 initially outperformed MSK Replicator in raw end-to-end latency. By tuning the producer.linger.ms and compression.type parameters in MM2, we achieved a replication lag of roughly 850ms. Out of the box, MSK Replicator hovered around 1.2s to 1.5s.

However, MSK Replicator showed superior consistency. Under burst loads (spiking to 100 MB/s), the managed replicator scaled its internal resources faster than our standard Horizontal Pod Autoscaler (HPA) logic for the MM2 cluster, preventing the massive lag spikes we saw with the self-hosted solution.

2. Offset Translation:
One critical feature for Active/Passive DR is preserving consumer offsets. MSK Replicator handles __consumer_offsets translation automatically and seamlessly. With MM2, while supported, we found edge cases where consumer groups failed to resume exactly where they left off without manual intervention or the use of external tools like MirrorMaker 2 Checkpoint Connector.

For high-frequency trading or real-time fraud detection where every millisecond counts, the ability to fine-tune MM2 might be necessary. for 95% of enterprise use cases, the sub-second difference is negligible compared to the stability MSK provides.

Round 3: The Cost Analysis (TCO)

This is where the decision usually gets made. The pricing models for these two approaches are vastly different, and the "cheaper" option depends entirely on your scale.

AWS MSK Replicator Pricing:
AWS charges an hourly rate for the Replicator Units (MCUs) plus a per-GB fee for data replication. This is on top of standard cross-region data transfer costs.

MirrorMaker 2 Pricing:
You pay for the EC2/EKS compute and standard cross-region data transfer. There is no "premium" fee for the software itself.

The Break-Even Point

Our analysis suggests a clear divergence:

• Low to Medium Throughput (< 20 MB/s): MSK Replicator is often cheaper or cost-neutral when you factor in the engineering hours required to maintain an MM2 cluster. The "peace of mind" tax is low.
• High Throughput (> 100 MB/s): The per-GB replication fee of MSK Replicator starts to scale aggressively. At high volumes, running a dedicated fleet of Spot Instances for MM2 can result in 30-40% savings on the infrastructure bill.

However, CTOs must ask: What is the cost of a failed DR switchover? If your team is small, the operational risk of managing MM2 likely outweighs the infrastructure savings.

Choosing between AWS MSK Replicator and MirrorMaker 2 isn't just a technical decision; it's a strategic one regarding resource allocation. If your organization demands granular control over network packets and you have a dedicated DevOps team to tune the JVM, MirrorMaker 2 remains the performance king.

However, for most enterprises leveraging the cloud to reduce operational toil, AWS MSK Replicator offers a compelling, resilient solution that integrates deeply with the AWS ecosystem. It trades a small amount of latency and cost for significantly higher reliability and ease of use.

Need help architecting your Kafka strategy?
At Nohatek, we specialize in building resilient, cloud-native data platforms. Whether you need to optimize your current Kafka clusters or design a multi-region disaster recovery plan, our team is ready to help you build a system that doesn't just survive outages, but thrives in them.