# Layer 3 · Cloud & Infrastructure

URL: https://justuju.org/layer/cloud-infrastructure/

Turns racks of chips into rentable, schedulable clusters for training and serving models.

Gives the layer above: On-demand clusters, storage and networking that teams can train and serve models on.
Needs from the layer below: Accelerators and interconnect from Compute Hardware, housed and powered by Physical & Energy.

## Concepts

- [Cluster networking](https://justuju.org/concept/cluster-networking/): The very fast network that lets thousands of accelerators share results every training step, so the whole cluster behaves like one computer.
- [GPU clusters & orchestration](https://justuju.org/concept/gpu-clusters/): Thousands of accelerators networked and scheduled to act as one machine for training or serving.
- [GPU clouds & neoclouds](https://justuju.org/concept/gpu-clouds/): Companies that own huge GPU clusters and rent slices of them by the hour, from big general clouds to specialist GPU-only providers.
- [Training vs inference infrastructure](https://justuju.org/concept/training-vs-inference/): Training needs one giant, tightly linked cluster for weeks; serving answers needs many smaller copies close to users, sized for speed and cost per request.
- [Running locally vs in the cloud](https://justuju.org/concept/local-vs-cloud/): Open-weight models can run on your own hardware at home, trading the cloud's scale and convenience for privacy, control and a fixed cost.

---
Justuju · https://justuju.org/ · Content CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Quote with a link to the page.