Friday, September 5, 2008

Data Center Tiers

A four tier system that provides a simple and effective means for identifying different data center site infrastructure design topologies. The Uptime Institute's tiered classification system is an industry standard approach to site infrastructure functionality addresses common benchmarking standard needs. The four tiers, as classified by The Uptime Institute include the following:

Tier 1: composed of a single path for power and cooling distribution, without redundant components, providing 99.671% availability.
Tier II: composed of a single path for power and cooling distribution, with redundant components, providing 99.741% availability
Tier III: composed of multiple active power and cooling distribution paths, but only one path active, has redundant components, and is concurrently maintainable, providing 99.982% availability
Tier IV: composed of multiple active power and cooling distribution paths, has redundant components, and is fault tolerant, providing 99.995% availability.

Tier I sites will have computer power distribution and cooling but may not have raised floors, UPSes, or engine generators. The critical load on these systems is up to 100 percent of N. Even with a UPS or generator, they likely are single-module systems and have many single points of failure. The infrastructure should be completely shut down on an annual basis to perform preventive maintenance and repair work. Urgent situations may require more frequent shutdowns. Tier IV data centers have all the bells and whistles; everything needed to keep them running without ever shutting down for maintenance, no matter what happens.

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