A single Prometheus instance can typically ingest over a million metrics every 15 seconds from thousands of targets. To increase high availability, a second Prometheus server can be added to scrape the same targets. After around 1.5 million scrapes or 5,000 exporters, the Prometheus instance may need to be split into shards to improve scalability. The Thanos project can then be introduced to provide a single clustered Prometheus view while storing historical data in object storage, allowing the monitoring system to scale to millions of metrics.