Deterministic simulation testing is becoming a gold standard for mission-critical software testing. The FoundationDB team popularized this approach by building a deterministic simulator before writing data to actual disks. This method has been adopted by other teams, including the WarpStream team at Datadog, which used it to build a robust columnar storage engine. The WarpStream team leveraged object storage and deterministic simulation testing to accelerate development and ensure correctness. They integrated Antithesis, a bespoke hypervisor that deterministically simulates entire Docker containers and injects faults, to further improve testing efficiency. Antithesis automatically instruments software, detects rare behavior, and explores code branches concurrently, allowing for faster testing times and reduced costs. By using Antithesis, the WarpStream team was able to catch bugs that had evaded traditional testing methods, including a data race in their instrumentation library and an extremely rare data loss bug. The team believes that deterministic simulation testing with tools like Antithes is a more robust and sustainable path forward for the industry than traditional Jepsen-style testing.