Exin Exam CDCP Topic 2 Question 23 Discussion

The requirement of Concurrently Maintainability becomes relevant starting from Rated-3, according to the Uptime Institute Tier Classification System1. Concurrently Maintainability means that any component or system in the data centre can be maintained or replaced without affecting the availability of the IT equipment. This requires having redundant capacity components and multiple independent distribution paths serving the IT equipment. Rated-3 data centres are designed to achieve Concurrently Maintainability and have a minimum uptime of 99.982%. Rated-4 data centres also have Concurrently Maintainability, but they also have Fault Tolerance, which means that they can withstand any single unplanned event without affecting the availability of the IT equipment. Rated-4 data centres have a minimum uptime of 99.995%. Rated-1 and Rated-2 data centres do not have Concurrently Maintainability, as they have only one distribution path serving the IT equipment and no redundant capacity components. Rated-1 data centres have a minimum uptime of 99.671% and Rated-2 data centres have a minimum uptime of 99.741%.

1: Uptime Institute Tier Classification System2, page 1, section 1 2: Data Center Tiers Classification Explained: (Tier 1, 2, 3, 4)3, page 1, section 1 3: Data Center Tier Standards4, page 1, section 1