Fundamental Requirements
- As defined by the Uptime Institute, a concurrently maintainable data center has redundant capacity components and multiple independent distribution paths serving the computer equipment. Only one distribution path is required to serve the computer equipment at any time.
- All IT equipment is dual-powered and installed properly to be compatible with the topology of the site’s architecture. Transfer devices, such as point-of-use switches, must be incorporated for computer equipment that does not meet this specification.
Performance Confirmation Tests
- Each and every capacity component and element in the distribution paths can be removed from service on a planned basis without impacting any of the computer equipment.
- There is sufficient permanently installed capacity to meet the needs of the site when redundant components are removed from service for any reason.
Operational Impacts
- The site is susceptible to disruption from unplanned activities. Operational errors of site infrastructure components may cause a computer disruption.
- An unplanned outage or failure of any capacity system will impact the computer equipment.
- An unplanned outage or failure of a capacity component or distribution element may impact the computer equipment.
- Planned site infrastructure maintenance can be performed by using the redundant capacity components and distribution paths to safely work on the remaining equipment.
- During maintenance activities, the risk of disruption may be elevated. (This maintenance condition does not defeat the Tier rating achieved in normal operations.)
Engine-Generator Systems
Tier III and IV engine-generator systems are considered the primary power source for the data center. The local power utility is an economic alternative. Disruptions to the utility power are not considered a failure, but rather an expected operational condition for which the site must be prepared.
Site on Engine-Generator Power
A Tier III or IV engine-generator system, along with its power paths and other supporting elements, shall meet the Concurrently Maintainable and/or Fault Tolerant performance confirmation tests while they are carrying the site on engine-generator power.
Manufacture’s Run Time Limitation
Engine generators for Tier III and IV sites shall not have a limitation on consecutive hours of operation when loaded to “N” demand.
Regulatory Run Time Limitation
Engine-generator systems often have an annual regulatory limit on operating hours driven by emissions. These environmental limits do not impact the consecutive hours of operation constraint established in this section.