📖 Glossary

Term	Meaning
Autoscaling	Extra instances added automatically to a customer's VMs or Kubernetes cluster when they are busy, and removed when the load drops.
Backbone	The cable tray linking the aisles of a server room.
Cable manager	A 1U accessory that routes the cables of nearby devices neatly along the rack.
Cold / hot aisle	The aisle in front of the racks (cold, where servers take in air) and behind them (hot, where they blow it out — and where the cables are).
COP	Coefficient of performance of a cooling unit: heat removed per unit of electricity drawn. Higher is better.
DAC	Direct-attach copper: a short, cheap, fast cable between two SFP or QSFP cages. Reaches only a few metres.
Degraded	A unit that runs, but badly (saturated server, slow or lossy network). Still billed, but counts as unavailable.
Disconnected	A unit that can't be reached (server off or failed, no network path). Not billed, counts as unavailable.
Execution unit	One instance of a service you sold (a VM, a database…) running on one of your servers.
Failover	Switching traffic to a backup path when the main one fails.
Fibre	An optical cable with its two optics, for long distances. Expensive.
L2 / L3	Simple switching over a single path / routing over several paths at once with instant failover.
Load balancing	Spreading traffic over several links at the same time.
Management port	The socket that opens a device's management page instead of carrying data.
N+1	Having one more unit (cooling, power…) than strictly needed, so that a single failure changes nothing.
Off-peak / peak hours	Night hours with cheap electricity / day hours with expensive electricity.
Operator uplink	The box in the operator rack that connects your building to the Internet.
Overcommitment	Selling more CPU or network than your servers physically have, betting that not everyone needs it at once.
Pending	A unit that found no server with enough room. Not billed, counts as unavailable.
Prospect	A potential customer, waiting for your answer on the Prospects page.
QSFP28	A 100 Gb/s network cage, for network cores, routers and fast Internet uplinks.
Rack	The cabinet in which servers and network devices are mounted.
Reputation	Your standing on the market (0 to 100): it drives how many prospects show up, tier unlocks and renewals.
RJ45	The classic copper network socket. Capped at 1 Gb/s in the game.
Saturation	Real demand above the capacity of a server or a link: everything on it suffers.
Shedding	Switching off whole racks when your power demand exceeds what your grid can deliver.
SFP+ / SFP28	Network cages for 10 / 25 Gb/s links, taking DAC or fibre cables.
Single point of failure	A device or cable whose failure alone cuts services off, for lack of a backup path.
SLA	Service Level Agreement: the availability you promise a customer, and its measured value.
Spine	A very fast (100G) switch linking several network cores and routers together.
Tier	A customer's category — Starter, Pro, Business, Enterprise — setting its needs, its pay and its demands.
Transformer	Equipment in the electrical room that brings power to your racks. Their total sets (part of) your available power.
U	Rack unit: the height slot of a rack (4.45 cm). A 1U server takes one, a 2U server two.
Uplink	A switch's fast port used to connect it to the rest of the network.
vCPU	A virtual processor. A server offers two per physical core.