Uptime Institute’s “Data Center Site Infrastructure Tier Standard: Topology”

The Uptime Institute is an unbiased international advisory organization and a leader in data center design and management. The institute’s “Data Center Site Infrastructure Tier Standard: Topology” document provides the baseline that many enterprises use to rate their data center designs.

The document describes a four-tiered architecture for data center design, with each tier including fundamental requirements, performance confirmation tests, and operational impacts. Each tier is progressively more secure, reliable, and redundant in its design and operational elements than the one that precedes it.

Using the Tier Standard During Data Center Assessment

Data center operators frequently utilize the Tier Standard and awarded certification when promoting their data center.

The following information on the four-tier design for data centers is taken from the “Data Center Site Infrastructure Tier Standard”:

Tier I: Basic Site Infrastructure

The fundamental requirements:

• Nonredundant capacity components (servers, routers, switches).
• Single, nonredundant distribution path serving the critical environment.
• A dedicated space for IT systems; an uninterruptible power supply (UPS) to filter power spikes, sags, and momentary outages; dedicated cooling equipment; and an engine generator to protect IT functions from extended power outages.
• Twelve hours of on-site fuel storage for engine generator(s).

The performance confirmation tests:

• There is sufficient capacity to meet the needs of the site.

• Planned work will require most or all the site infrastructure systems to be shut down, affecting critical environment, systems, and end users.

The operational impacts:

• The site is susceptible to disruption from both planned and unplanned activities. Operation (human) errors of site infrastructure components will cause a data center disruption.
• An unplanned outage or failure of any capacity system, capacity component, or distribution element will impact the critical environment.

Tier II: Redundant Site Infrastructure Capacity Components

The fundamental requirements:

• Has redundant capacity components (servers, routers, switches).
• A single, nonredundant distribution path serving the critical environment. The redundant components are extra engine generators, UPS modules and energy storage, chillers, heat rejection equipment, pumps, cooling units, and fuel tanks.
• Twelve hours of on-site fuel storage for “N” capacity.

The performance confirmation tests:

• Redundant capacity components can be removed from service on a planned basis without causing any of the critical environments to be shut down.
• Removing distribution paths from service for maintenance or other activity requires shutdown of critical environment.
• There is sufficient permanently installed capacity to meet the needs of the site when redundant components are removed from service for any reason.

The operational impacts:

• The site is susceptible to disruption from both planned activities and unplanned events. Operation (human) errors of site infrastructure components may cause a data center disruption.
• An unplanned capacity component failure may affect the critical environment. An unplanned outage or failure of any capacity system or distribution element will affect the critical environment.

Tier III: Concurrently Maintainable Site Infrastructure

The fundamental requirements:

• Redundant capacity components.
• Multiple independent distribution paths serving the critical environment. Only one distribution path is required to serve the critical environment at any time.
• All IT equipment is dual-powered as defined by Uptime Institute’s Fault-Tolerant Power Compliance Specification, Version 2.0, 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 critical environments that do not meet this specification.
• Twelve hours of on-site fuel storage for “N” capacity.

The performance confirmation tests:

• Concurrently maintainable components can be removed from service on a planned basis without causing any of the critical environments to be shut down.
• A distribution path may be removed from service for maintenance or other activity and does not require a shutdown of critical environment.
• There is sufficient permanently installed capacity to meet the needs of the site when redundant components are removed from service for any reason.

The operational impacts:

• The site has little susceptibility to disruption from both planned activities and unplanned events. Operation (human) errors of site infrastructure components may cause a data center disruption if all redundant paths are disabled.
• An unplanned capacity component failure does not affect the critical environment.
• An unplanned outage or failure of any capacity system or distribution element will not affect the critical environment.

Tier IV: Fault-Tolerant Site Infrastructure

The fundamental requirements:

• Multiple independent, physically isolated systems that provide redundant capacity components and multiple independent, diverse, active distribution paths simultaneously serving the critical environment.
• Complementary systems and distribution paths must be physically isolated from one another (compartmentalized) to prevent any single event from simultaneously impacting both systems and distribution paths.
• Continuous cooling is required.
• Twelve hours of on-site fuel storage for “N” capacity.

The performance confirmation tests:

• Redundant capacity components can be removed from service on a planned basis without causing any of the critical environments to be shut down.
• Removing distribution paths from service for maintenance or other activity requires no shutdown of the critical environment.
• There is sufficient permanently installed capacity to meet the needs of the site when redundant components are removed from service for any reason.

The operational impacts:

• The site is not susceptible to disruption from either planned activities and unplanned events. Operation (human) errors of site infrastructure components will not cause a data center disruption.
• An unplanned capacity component failure will not affect the critical environment. An unplanned outage or failure of any capacity system or distribution element will not affect the critical environment.

Summary Table