Data center tier
Data center tier refers to a standardized classification system that categorizes data centers based on their infrastructure design, reliability, redundancy, and availability. The tier system provides a way to evaluate and compare the resilience and performance capabilities of different data centers. The most commonly used tier system is the one developed by the Uptime Institute, a globally recognized organization for data center reliability and efficiency.
Classification system of data center tier by the Uptime Institute
The Uptime Institute’s tier classification system consists of four tiers:
1) Tier I: Tier I data centers have basic infrastructure components and provide a non-redundant environment for IT equipment. They have a single path for power and cooling, meaning they are susceptible to planned and unplanned downtime. They typically have an availability of approximately 99.671%, with a maximum of 28.8 hours of annual downtime.
2) Tier II: Tier II data centers offer some redundant components and infrastructure, providing improved reliability compared to Tier I. They have redundant power and cooling distribution paths but lack redundant components within those paths. They generally achieve an availability of around 99.741%, with a maximum of 22 hours of annual downtime.
3) Tier III: Tier III data centers have a concurrently maintainable design, ensuring that individual infrastructure components can be taken offline for maintenance or replacement without disrupting the IT operations. They feature multiple independent power and cooling distribution paths, allowing for maintenance without downtime. Tier III data centers aim for an availability of approximately 99.982%, resulting in a maximum of 1.6 hours of annual downtime.
4) Tier IV: Tier IV data centers provide the highest level of reliability and fault tolerance. They have redundant components, multiple independent distribution paths, and are designed to withstand individual equipment failures or planned maintenance without any disruption to IT operations. Tier IV data centers offer an availability of approximately 99.995%, with a maximum of 0.4 hours of annual downtime.
These tiers help data center owners, operators, and clients understand the level of infrastructure resilience and availability provided by a facility. Higher-tier data centers generally require more redundant systems and are designed to provide better uptime and fault tolerance. However, achieving higher tiers involves increased costs due to the additional infrastructure and redundancy requirements.