# Grafana Mimir — Horizontally Scalable Prometheus Storage

> Long-term metrics store for Prometheus and OpenTelemetry: multi-tenant, highly available, and queryable at a billion active series.

## Install

Save in your project root:

# Grafana Mimir — Horizontally Scalable Prometheus Storage

## Quick Use
```bash
# Single-binary monolith for local testing
docker run -d --name mimir -p 9009:9009 
  -v $(pwd)/mimir.yaml:/etc/mimir.yaml 
  grafana/mimir:latest -config.file=/etc/mimir.yaml

# Remote-write from Prometheus
# remote_write:
#   - url: http://localhost:9009/api/v1/push
#     headers: { X-Scope-OrgID: team-a }
```

## Introduction
Grafana Mimir forked Cortex in 2022 and took it to a new scale: benchmarks show a single cluster holding over one billion active series with sub-second query latency. It speaks the Prometheus remote-write, PromQL, and OpenTelemetry OTLP protocols so existing dashboards and agents plug in without change.

## What Mimir Does
- Stores Prometheus samples in object storage (S3, GCS, Azure, MinIO) indefinitely.
- Serves PromQL queries across tenants and time windows with query sharding.
- Ingests OTLP metrics alongside Prometheus remote-write.
- Provides a managed ruler for recording and alerting rules per tenant.
- Runs alertmanagers per tenant with a shared ring for HA.

## Architecture Overview
Microservices talk over gRPC and share a memberlist ring: distributor, ingester, querier, query-frontend, store-gateway, compactor, ruler, alertmanager. Ingesters buffer 2 hours of data and flush TSDB blocks to object storage; store-gateways index those blocks for historical queries. A deployment runs as three classes of pods (write, read, backend) for simplicity, or 20+ microservices for maximum tuning.

## Self-Hosting & Configuration
- Monolithic mode: one binary, perfect for labs; scale to microservices when you outgrow it.
- Object store is mandatory — S3-compatible backends keep the stack cheap.
- Helm chart `grafana/mimir-distributed` is the production-recommended install.
- Authenticate tenants via `X-Scope-OrgID`; pair with an auth proxy or OIDC gateway.
- Tune `-blocks-storage.tsdb.retention-period` and compactor schedule for cost.

## Key Features
- Horizontally scalable: add ingesters or queriers — no sharding config to hand-edit.
- Query sharding splits PromQL across queriers for near-linear speedups.
- Tenants are first-class: quota, retention, and ruler scheduling are per team.
- 100% PromQL compatible — existing dashboards move with zero rewrites.
- Built-in cardinality explorer and overrides-exporter surface hot metrics.

## Comparison with Similar Tools
- **Cortex** — the parent project; Mimir has faster queries and simpler ops.
- **Thanos** — sidecar-first design; shares the object-store idea but different topology.
- **VictoriaMetrics** — single-binary rival, MIT license, smaller footprint.
- **Prometheus + remote storage** — fine for one team; lacks multi-tenant and HA rulers.
- **DataDog / Chronosphere** — managed SaaS; Mimir is the self-hosted alternative.

## FAQ
**Q:** License?
A: AGPL-3.0 — safe to self-host, commercial embedding requires care.

**Q:** Migration from Cortex?
A: Supported path; Mimir reads existing Cortex blocks and configs directly.

**Q:** Alertmanager?
A: Mimir ships a multi-tenant Alertmanager; you can also forward to an external one.

**Q:** Cost at scale?
A: Object storage + compute; Grafana Labs reports ~2x cheaper than Thanos at billion-series scale in their benchmarks.

## Sources
- https://github.com/grafana/mimir
- https://grafana.com/docs/mimir/latest/

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Source: https://tokrepo.com/en/workflows/6c28dae8-3919-11f1-9bc6-00163e2b0d79
Author: AI Open Source