Infrastructure Monitoring Comparison: Prometheus 2.52 vs. Grafana Mimir vs. Thanos 0.35

Infrastructure monitoring is a critical component of modern DevOps workflows, enabling teams to track system health, troubleshoot issues, and optimize performance. Three tools dominate the metrics monitoring landscape: Prometheus (the de facto open-source standard), Grafana Mimir (Grafana’s scalable long-term storage solution), and Thanos (a distributed Prometheus extension for global visibility and long-term retention). This article compares the latest versions — Prometheus 2.52, Grafana Mimir, and Thanos 0.35 — across key criteria to help you choose the right tool for your needs.

Tool Overviews

Prometheus 2.52

Prometheus is an open-source monitoring and alerting toolkit originally built by SoundCloud, now a CNCF graduated project. Version 2.52, released in Q2 2024, introduces several improvements: enhanced TSDB compression reducing disk usage by up to 15% for high-cardinality metrics, native support for UTF-8 metric names, upgraded Go runtime to 1.22 for better performance and security patches, and improved PromQL query planning for faster execution of complex queries. By default, Prometheus stores metrics locally for 15 days, pulls metrics via HTTP scrapes, and uses PromQL for querying and alerting. It is designed for single-node or federated deployments, with no native horizontal scaling or long-term storage.

Grafana Mimir

Grafana Mimir is a horizontally scalable, multi-tenant metrics backend compatible with the Prometheus remote write API and PromQL. Launched by Grafana Labs in 2022, it is designed to handle petabytes of long-term metrics data, separating ingest, storage, and query workloads into independent, scalable components. Mimir uses object storage (AWS S3, Google Cloud Storage, Azure Blob Storage) for durable long-term retention, with in-memory caching for recent data to deliver fast query performance. It integrates natively with Grafana for visualization and alerting, and supports multi-tenancy with per-tenant resource isolation and rate limiting.

Thanos 0.35

Thanos is an open-source project that extends Prometheus to support long-term storage, global query visibility across multiple Prometheus instances, and high availability. Version 0.35, released in early 2024, adds improved Store Gateway caching to reduce query latency for historical data, support for additional object storage backends (including MinIO and Alibaba OSS), enhanced downsampling for 5-minute and 1-hour intervals, and tighter integration with Prometheus 2.52’s new features. Thanos deploys a Sidecar alongside each Prometheus instance to upload local TSDB blocks to object storage, and provides Thanos Query to execute PromQL queries across all connected Prometheus instances and stored historical data.

Key Comparison Criteria

We evaluate the three tools across seven critical dimensions for infrastructure monitoring: scalability, storage architecture, query performance, high availability, multi-tenancy, ease of setup, and cost.

1. Scalability

Prometheus 2.52: Single-node by default, with vertical scaling (adding CPU/memory) as the only native option. Horizontal scaling requires Prometheus federation, a complex and brittle approach that duplicates metrics across instances. Not suitable for deployments with more than 1 million active series or multi-cluster environments.

Grafana Mimir: Horizontally scalable across all core components (distributors, ingesters, query schedulers, compactors). It can handle tens of millions of active series, supports auto-scaling via Kubernetes, and provides native multi-cluster support out of the box. Ingest and query capacity can be scaled independently based on workload.

Thanos 0.35: Horizontally scalable via decoupled components (Sidecar, Store Gateway, Query, Compactor). It supports large-scale deployments with millions of active series, but requires more manual configuration than Mimir to scale components effectively. Store Gateway and Query nodes can be scaled independently, but ingester scaling is tied to underlying Prometheus instances.

2. Storage Architecture

Prometheus 2.52: Uses local time-series database (TSDB) for short-term storage, with a default retention period of 15 days. No native long-term storage; teams must configure remote write to external systems (like Mimir or Thanos) for retention beyond the default period.

Grafana Mimir: Uses a tiered storage architecture: recent data is stored in-memory in ingesters, with durable storage in object storage. Compactors periodically merge and downsample data in object storage to optimize query performance for historical data. Data is replicated across 3 ingester peers by default for durability, with no reliance on local Prometheus storage.

Thanos 0.35: Relies on Prometheus’s local TSDB for short-term storage, with the Sidecar component uploading immutable TSDB blocks to object storage every 2 hours. Thanos supports downsampling of historical data to 5-minute and 1-hour intervals to reduce storage costs and improve query performance for long-range queries. No native in-memory caching for recent data, though third-party caching layers can be added.

3. Query Performance

Prometheus 2.52: Delivers sub-second query performance for recent data (stored locally), but performance degrades significantly for queries spanning more than a few days, or for high-cardinality metrics. No support for global queries across multiple Prometheus instances.

Grafana Mimir: Provides fast query performance for both recent and historical data via query schedulers that parallelize query execution across ingesters and object storage, plus built-in caching for frequently accessed data. Supports all PromQL features, plus Grafana-specific query optimizations. Global queries across all stored metrics are executed in milliseconds for most workloads.

Thanos 0.35: Thanos Query enables global PromQL queries across all connected Prometheus instances and object storage. Version 0.35 improves query performance via Store Gateway caching, but large historical queries can still be slower than Mimir, especially for high-cardinality metrics. No native parallel query execution across object storage blocks.

4. High Availability (HA)

Prometheus 2.52: No native HA support. A single Prometheus instance is a single point of failure; teams must deploy multiple federated instances or use external tools to replicate data, which adds complexity and risk of data inconsistency.

Grafana Mimir: Native HA with no single point of failure. All components are replicated, ingesters replicate data to 3 peers, and query schedulers automatically retry failed queries. Supports multi-zone deployment to tolerate zone-level outages.

Thanos 0.35: HA is achieved via redundant Prometheus instances (each with a Sidecar), replicated Thanos Query and Store Gateway nodes, and object storage durability. Requires careful configuration to avoid single points of failure (e.g., ensuring multiple Store Gateway nodes are deployed).

5. Multi-Tenancy

Prometheus 2.52: No native multi-tenancy. Teams must deploy separate Prometheus instances per tenant, which increases operational overhead and cost.

Grafana Mimir: Built-in multi-tenancy with strict tenant isolation, per-tenant rate limiting, resource quotas, and billing meters. Ideal for SaaS providers or organizations with shared monitoring infrastructure across teams.

Thanos 0.35: Multi-tenancy is supported via tenant labels or separate Thanos deployments per tenant, but lacks native isolation or resource controls. Additional configuration (e.g., using Prometheus relabeling) is required to implement tenant-level rate limiting.

6. Ease of Setup

Prometheus 2.52: Extremely easy to set up: download a single binary, write a 10-line YAML config, and start scraping metrics in minutes. Ideal for small teams, single Kubernetes clusters, or proof-of-concept deployments.

Grafana Mimir: More complex to set up, with a typical deployment requiring Kubernetes and 10+ microservice components. Grafana provides official Helm charts and a managed service (Grafana Cloud Mimir) to reduce operational overhead. Teams familiar with Kubernetes can deploy Mimir in a few hours using Helm.

Thanos 0.35: Steep learning curve: requires deploying Sidecars alongside all Prometheus instances, plus 4+ independent Thanos components (Query, Store Gateway, Compactor, Ruler). Configuration is complex, with many interdependent settings. Best suited for teams with experience managing distributed systems.

7. Cost Considerations

Prometheus 2.52: Free open-source software with minimal infrastructure costs (a single small VM or pod can handle most small deployments). No long-term storage costs unless using external systems.

Grafana Mimir: Free open-source, but requires compute resources for Mimir components and object storage costs (typically $0.02–$0.05 per GB per month). Grafana Cloud Mimir offers a managed service with per-active-series pricing, starting at $0.10 per 1000 series per month.

Thanos 0.35: Free open-source, with costs for compute resources to run Thanos components and object storage. No official managed service, but major cloud providers (AWS, GCP) offer managed Thanos as part of their observability suites.

Ideal Use Cases

• Prometheus 2.52: Small to medium deployments, single Kubernetes clusters, short-term monitoring (retention < 15 days), teams new to metrics monitoring, or as a local scraper for Mimir/Thanos.
• Grafana Mimir: Large-scale deployments (10M+ active series), multi-cluster or hybrid cloud environments, long-term metrics retention (years), multi-tenant SaaS platforms, teams already using Grafana for visualization.
• Thanos 0.35: Organizations with existing Prometheus deployments needing long-term storage and global query, hybrid cloud environments with disparate Prometheus instances, teams comfortable with complex distributed systems and custom configuration.

Conclusion

All three tools are industry-leading solutions for infrastructure monitoring, with distinct strengths. Prometheus 2.52 remains the best choice for simplicity, small-scale deployments, and teams getting started with metrics monitoring. Grafana Mimir is the top pick for organizations needing a scalable, managed, multi-tenant long-term storage solution with native Grafana integration. Thanos 0.35 is ideal for teams with existing Prometheus deployments that need flexible, open-source long-term storage and global query capabilities without vendor lock-in. Evaluate your scale, existing toolchain, and operational capacity to select the tool that aligns with your infrastructure monitoring needs.