Grafana Mimir 3.0 launched in early November 2025 — and it’s far more than a version bump. It’s a complete architectural overhaul designed to fix long-standing pain points for SRE and DevOps teams, especially the dreaded spike in ingestion latency whenever someone runs a heavy sum by query over 30 days. Today, Khun Tan, Platform Services Engineer will walk us through what’s new in Mimir 3.0 and how it can make your day-to-day operations significantly smoother.
1) Kafka Buffer: A Clean Separation Between Read and Write Paths
The old problem, Ingesters previously handled both write traffic and read queries. When queries were heavy, CPU and memory contention caused ingestion delays, data loss, or even OOM crashes.
The new approach, Mimir 3.0 uses Kafka (or WarpStream) as a write buffer.
- The distributor shards incoming data directly into Kafka partitions.
- Ingesters consume from those partitions at their own pace.
The result: Query load no longer impacts the write path, making ingestion far more stable and resilient.
2) MQE: A Faster, Lighter Default Query Engine
The Mimir Query Engine (MQE) is now the default engine.
- Streaming-first execution dramatically reduces memory usage
- Up to 92% lower peak memory usage in benchmarks
- Significant performance boost for high-cardinality queries
- Fully PromQL-compatible, so dashboards require no changes
3) Easier Scaling + Real Cost Savings
Separating read and write responsibilities gives you flexible scaling:
- Scale query-side and write-side independently
- No need to over-provision entire clusters
- Grafana Labs reports up to 15% cost reduction for large clusters due to more efficient resource usage
Summary
Mimir 3.0 evolves from being just a scalable Prometheus replacement to becoming a true enterprise-grade telemetry backend. You get:
- Better stability from cleanly separated responsibilities
- Faster and more efficient querying via MQE
- Improved resource control and lower operational cost
If you’re still on Mimir 2.x, monitor your ingesters during query spikes.
If you see contention, it’s time to plan a migration to the new Ingest Storage Architecture.
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