What is TIER IV?

TIER IV is the highest classification level for a data center (DC) according to the Uptime Institute methodology, ensuring a fully fault-tolerant infrastructure. A TIER IV data center guarantees that the failure of any single component, distribution path, or even certain concurrent events will not result in interruption of IT services.

Key requirements include redundancy of critical systems based on a 2N (or 2N+1) configuration, fully independent and physically isolated power, cooling, and distribution paths, diesel generator systems, uninterruptible power supply (UPS) systems, and automatic transfer mechanisms without load interruption. The expected annual availability is 99.995%, corresponding to a maximum downtime of approximately 26.3 minutes per year. Uptime Institute certification includes a review of design documentation, inspection of the constructed facility, and verification of operational procedures to confirm full compliance with the TIER IV standard.