What is a data center Tier?
The Telecommunications Industry Association, in 2005, published the Telecommunications Infrastructure Standard for Data Centers (ANSI/TIA-942) and since then has been amended in 2008 and again in 2010, giving Data Centers 4 Tiers. Tier 1 being the most basic and Tier 4 being the most redundant, complex and expensive.
Here is a basic breakdown of the Tiers:
Tier 1 = Non-redundant capacity (single uplink & Servers)
Tier 2 = Tier 1 + Redundant site infrastructure
Tier 3 = Tier 1 + Tier 2 + Dual-powered equipment & multiple uplinks
Tier 4 = Tier 1 + Tier 2 + Tier 3 + all components are fully fault-tolerant including uplinks, storage, chillers, HVAC systems, severs and everything is dual-powered.
What does this really mean? A lot of it has to do with negating downtown and creating redundancy, reliability and maintainability.
Tier 1: trying to ensure 99.671% availability.
Tier 2: trying to ensure 99.741% availability.
Tier 3: trying to ensure 99.982% availability.
Tier 4: trying to ensure 99.995% availability.
These percentages do not seem like a big difference but you must consider that there are 525,600 minutes in a year so acceptable downtime translates into:
Tier 1 allows for 1729 minutes of downtime.
Tier 2 allows for 1361 minutes of downtime.
Tier 3 allows for 94 minutes of downtime.
Tier 4 allows for 26 minutes of downtime.
The official certifying body is the Uptime Institute found here: www.uptimeinstitute.com Hopefully this clarifies the difference in Data center tiers for your new or upgraded data center. If you have more specific questions feel free to email them to firstname.lastname@example.org.