Datacenter Terminologies

A concise reference of the essential power, cooling, networking, hardware, and operational terms used across modern datacenter environments. Built to give engineers and operators a shared, accurate vocabulary for designing, troubleshooting, and scaling infrastructure.

 

Power Terminology

A/B Power : Two completely independent power feeds providing redundancy so a server stays online if one path fails.

3‑Phase Power: A high‑capacity electrical system using three 120°‑offset phases to deliver stable, efficient power.

UPS (Uninterruptible Power Supply):  Battery‑backed system that conditions power and provides ride‑through during utility → generator transitions.

PDU (Power Distribution Unit) : Large floor‑mounted unit that steps down and distributes power from UPS to RPPs and racks.

RPP (Remote Power Panel) : Panel that distributes branch circuits from PDUs to individual racks.

Rack PDU / ePDU : Strip inside the rack that distributes power to servers; often metered or switched.

Breaker : Protective device that trips when a circuit is overloaded.

Phase Balancing:  Evenly distributing load across Phase A/B/C to prevent breaker trips and overheating.

PSU (Power Supply Unit):  Converts AC to DC and feeds server components; supports redundancy (1+1, N+1).

VRM (Voltage Regulation Module): Steps down DC rails to precise voltages for CPUs, GPUs, and DIMMs.