Promscale is an open-source, scalable, and robust storage system for Prometheus metric data. It's built on top of TimescaleDB and PostgreSQL, providing full SQL support, advanced time-series analysis capabilities, and a robust ecosystem of tools and integrations. Promscale simplifies operations by storing all Prometheus metrics in a single centralized store, enabling cross-tenant queries, flexible control and permissions, and operational maturity. With multi-tenancy enabled, users can query data by tenant label or across tenants, while individual development teams' queries are restricted to their respective tenant's data. This allows organizations to centralize Prometheus data, unlock advanced analysis capabilities, and reduce operational complexity. Promscale supports both PromQL and SQL queries, enabling developers to use the language of their choice for querying and analyzing data. The system is designed to help large-scale systems achieve reliability and performance by providing a scalable and robust storage solution for Prometheus metrics.