The document explains a four-tier ranking system for data centers, established in 2005, that indicates their overall capabilities and service levels based on infrastructure, redundancy, and uptime. Tier I has 99.671% expected uptime with minimal redundancy, while Tier IV offers 99.995% uptime with fully fault tolerant systems. The document also highlights the drastic differences in potential downtime between the tiers, showing that Tier I can have up to 1,729 minutes of downtime annually compared to only 26 minutes for Tier IV.

1. Data Center Tiers Explained
A Data Cave Presentation

2. Why do we
need Tiers?

3. Some background
Why do we have tiers? What do they indicate?
• With so many data centers of
varying sizes, a standard was
needed that could be used to
consistently identify a data
center’s overall capabilities
and level of service.
• The 4-Tier ranking system was
established in 2005 to be this
unique standard for the data
center industry.
The criteria for each of the 4 tiers
primarily focuses on a data
center’s:
• Infrastructure
• Levels of redundancy
• Promised uptime level

4. Breaking down
the 4 Tiers

5. The Tier I Data Center
Expected Uptime:
99.671%
Single path for power and cooling to the server
equipment, with no redundant components.
Typically lacks features seen in larger data
centers, such as a backup cooling system or
generator.
Very little (if any) levels of redundancy.

6. The Tier II Data Center
Expected Uptime:
99.741%
Will typically have a single path for both power and
cooling, but will utilize some redundant components.
These data centers have some backup
elements, such as a backup cooling system
and/or a backup generator.
Some redundancy measures are active.

7. The Tier III Data Center
Expected Uptime:
99.982%
Multiple power and cooling distribution paths to
servers, to ensure availability if one path fails.
Multiple power sources for all IT equipment.
Considerably higher availability and uptime.
Specific procedures that allow for maintenance to be
done in the data center, without causing downtime.

8. The Tier IV Data Center
Expected Uptime:
99.995%
Fully meets all requirements for Tiers I-III.
Fully fault tolerant infrastructure; it can
function normally even in the event of 1 or
more equipment failures.
A truly maximum level of uptime.
Redundancy in everything: Multiple cooling units,
backup generators, power sources, chillers, etc.

9. What
Represents
Tier IV

10. What Tier IV Represents
A Tier IV ranking indicates that a data center can
maintain a truly maximum uptime level through its:
• Redundant components and supporting hardware
• Facility’s physical construction and security
• Fully fault tolerant infrastructure
• Internal processes/procedures

11. With uptime levels of 99.995%, a Tier IV data center could
experience up to 26 minutes of downtime annually.
Compare that to a Tier I data center: At 99.671% uptime, they can
see up to 1,729 minutes of downtime annually!
Fun fact:

12. Data Center Tiers Explained
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