May 2025 monthly summary focusing on key deliverables and business value across grafana/mimir and prometheus/docs. Highlights include feature delivery for Block-builder Scheduler Dashboard and Metrics in Mimir, along with comprehensive resource utilization dashboards; bug fix for governance documentation affiliation in Prometheus docs. Overall impact: improved observability, faster incident response, and governance accuracy.

Concise month-in-review for 2025-03 highlighting delivered resilience, reliability, and data integrity enhancements across Grafana Mimir and Mimir-Prometheus. Focus on business value, operational stability, and cross-repo collaboration.

February 2025 performance highlights for grafana/mimir. Key capabilities delivered and reliability improvements focused on the block-building path, with measurable observability gains and startup determinism.

January 2025: grafana/mimir — Block Builder Reliability: Data Integrity and Monitoring Enhancements. Delivered a new configuration option no_partially_consumed_region to ensure partitions are consumed to the cycle end, preventing partially consumed regions and boosting data integrity. Enhanced block builder monitoring by updating existing alerts and introducing critical alerts for timely notifications of issues. This work reduces data gaps, improves reliability of data pipelines, and strengthens observability.

December 2024 monthly recap for grafana/mimir focusing on stability and safe data ingestion. Implemented a Native Histograms Ingestion Safety Guard behind a feature flag to prevent hard failures when native histograms ingestion is disabled for a tenant. The change includes automated tests that verify ingestion occurs when enabled and is ignored when disabled, enabling safer rollouts and tenant isolation.

November 2024 monthly summary for Grafana Mimir workloads across grafana/mimir and grafana/mimir-prometheus. Key features delivered: - Centralized SoftAppendErrorProcessor introduced to standardize non-terminal error handling across ingesters and block builders, improving consistency and maintainability. (Commit: 5e6d24fb216fc52c6ae636b4e8ab3bc7ee003fa0; Message: Share the append error checking code between ingesters and block builders (#9745)) - Experimental support for 24-hour blocks for older out-of-order (OOO) data, including a new configuration flag to reduce pressure on compactors and ingesters when processing data spanning multiple past days. (Commit: 832d02b54e4e83c8da3ecc47586cf3a13e77dd94; Message: Add `blocks-storage.tsdb.bigger-out-of-order-blocks-for-old-samples` flag (#10035)) - Per-user global series limit safeguard to prevent spikes for smaller tenants, enhancing resource management and stability. (Commit: b941204548eec0c8f92e6a846620840e73393c39; Message: block-builder: Add basic series limit (#9983)) - Grafana Mimir Prometheus: Enable 24-hour OOO blocks for older samples through new option EnableBiggerOOOBlockForOldSamples and refactored compactOOO logic, with tests validating block creation and compatibility with Mimir’s maintenance strategy. (Commits: 3931e9c4fc4ef47c3b47cf9bb58311f5af469157; 8809a3ee19c9cf2221d7ca1480a0817fd611f4f4; Messages: Build 24h blocks for older OOO data (#751); Add a EnableBiggerOOOBlockForOldSamples option for the TSDB (#763)) Major bugs fixed / stability improvements: - Standardized error handling path to avoid divergent behavior across ingestion and block-building components, reducing runtime noise and misclassification. - Refined OOO data handling to better cope with older samples, decreasing risk of compaction bottlenecks and ingestion backpressure. Overall impact and accomplishments: - Improved reliability, scalability, and operational stability for multi-tenant deployments handling out-of-order data. - Reduced maintainability burden through centralized error handling and clearer configuration for OOO blocks. - Strengthened testing coverage around OOO block creation and compatibility with block maintenance strategy. Technologies / skills demonstrated: - Go, TSDB, and Mimir’s block maintenance architecture - Feature flags and configuration-driven behavior for OOO data - Cross-repo collaboration between grafana/mimir and grafana/mimir-prometheus - Focus on business value: better performance under out-of-order data, fair resource allocation, and predictable error handling across the stack.

Summary for 2024-10 (grafana/mimir): Key features delivered - Fixed a crash in Query-Frontend caused by malformed queries reaching the scheduler. Implemented a clientErr field in enqueueResult and ensured a 400 Bad Request is returned instead of crashing. Major bugs fixed - Stabilized the Query-Frontend/scheduler path under bad input by improving error propagation and input validation, preventing scheduler connection breakages. Overall impact and accomplishments - Increased reliability and resilience of the query path in grafana/mimir, reducing production incidents related to malformed queries and providing clearer feedback to clients. Technologies/skills demonstrated - Go, error handling, HTTP error semantics (400), queue/scheduler integration, targeted code changes with traceable commits. Commit reference for the change: - 587d234f00f2922cfb31438513c9536e757221ed ("query-frontend: Do not break scheduler connection on malformed queries (#9786)")