In 2011, the author humorously noted that Google possessed one of the world's limited number of computers. Fast forward to 2020, and the landscape has shifted toward "warehouse-sized computers," primarily through the rise of cloud computing. This transition has sparked interest in developing a comprehensive "Datacenter OS," a unified software solution that can manage large clusters of computers as if they were a single entity. While major tech companies like Google and Amazon are experimenting with their internal versions of this concept, a fully realized Datacenter OS for broader use remains absent. The author outlines essential components of this envisioned Datacenter OS, which include a cluster-wide file system, scalable key-value stores, and a message queuing system. These elements facilitate efficient resource management and data handling in large-scale distributed systems. Furthermore, the article emphasizes the need for tools that replicate familiar functionalities from single-machine operating systems in this new environment, such as observability features and debugging tools. The challenges are significant, particularly regarding security. Questions about user management, privilege escalation, and cross-service authentication are still largely unresolved. One of the author’s central ideas is that the development of a FOSS (Free and Open Source Software) Datacenter OS could represent a major advancement in computer science. This vision aims to enable users to install a single piece of software across multiple machines, effectively transforming them into a cohesive computing unit. The article suggests that understanding the functions of existing technologies in the context of a unified Datacenter OS can clarify their roles and how they might evolve. The author anticipates further discussions on topics such as security models and the integration of tools like Kubernetes into this framework.