Stand up Grafana Mimir for horizontally scalable, multi-tenant, long-term Prometheus + OTLP metrics storage. Covers monolithic / read-write / microservices deployment, S3 / GCS / Azure / filesystem block storage, Prometheus remote_write and OTLP ingestion, multi-tenancy with X-Scope-OrgID, ingester replication factor, compactor retention, and per-tenant limits. Use when running Mimir locally or on Kubernetes (Helm mimir-distributed), scaling Prometheus past a single node, picking ingest / query / backend split, configuring tenants and ingestion rate, debugging /ready 503s or 429 Too Many Requests, or pointing Grafana at a Mimir datasource — even when the user says "I need long-term Prometheus storage", "scale Prometheus", "multi-tenant metrics backend", "Cortex replacement", "remote_write target", or "store 10M active series" without naming Mimir.