A robust IT infrastructure matters more than ever. Server virtualization and cloud computing have brought new benefits and capabilities to IT organizations, but not without their own set of challenges and risks. High-performance and high-density services and applications are also on the rise while multiple application interdependencies have added to the number of IT environments being described as mission- or business-critical. Today, if your servers are down, so is your business. This paper presents an overview of Stratus uptime assurance technology for ftServer Systems. Fundamentals behind the purpose-built design — resilient servers, the Automated Uptime™ Layer, and proactive availability management — are explained in detail.