Datacenter Glossary

Physical barriers preventing hot exhaust and cold supply air from mixing in a data hall.

Central control system for a building's mechanical and electrical services including HVAC, power, and access control.

Annual CO₂ equivalent emissions from data centre energy divided by IT equipment energy in kWh.

Service model where customers own their servers but rent space, power, and connectivity from a facility operator.

Standalone precision cooling unit with an internal compressor used to cool server halls.

Fan-coil unit that uses chilled water from a central plant to cool data hall air. More efficient than CRAC at scale.

Inverse of PUE as a percentage. DCiE = (IT Power ÷ Total Power) × 100. Higher is better.

Software platform that monitors, measures, manages, and controls all data centre infrastructure and IT assets.

Cooling method bringing liquid directly to heat-generating components, enabling high-density rack deployments.

Measure of processor computational throughput, used to compare GPU and HPC system performance.

Using outside ambient air or water temperature to cool a facility without mechanical refrigeration, reducing energy use.

Rack arrangement separating hot exhaust air from cold supply air to improve cooling efficiency.

Very large data centre (typically 40+ MW) operated by cloud providers at massive scale with highly standardised infrastructure.

Specialist contractor responsible for integrating all building and IT systems into a single unified management platform.

Design model where one additional unit is deployed beyond the minimum required, so the system survives any single failure.

Device that distributes electrical power from a single high-amperage source to multiple rack-mounted devices.

Ratio of total facility power to IT equipment power. PUE 1.0 is perfect; the industry average is ~1.5.

Standard unit of vertical height for rack-mounted equipment. 1U = 44.45 mm (1.75 in).

Maximum acceptable age of data recoverable after a disruption — how much data loss is tolerable.

Maximum acceptable time to restore a service or system after a disruption.

Contractual commitment defining minimum acceptable uptime, response times, and service quality a provider must deliver.

Network switch at the top of a server rack that aggregates all server connections within that rack.

Full lifecycle cost of owning and operating IT infrastructure including capex, opex, cooling, space, and labour.

Battery-backed power system that maintains continuous supply to critical loads during mains failure.

Four-level system rating data centre design resilience from basic (Tier I) to fault-tolerant (Tier IV).

Annual site water usage (litres) divided by IT equipment energy (kWh). Lower is better.