Guide

CPU clusters forgive a mediocre network and a slow scheduler. GPU clusters do not. A job that spans many GPUs can spend most of its time waiting on data movement if the fabric or the scheduler is wrong. This topic is the infrastructure view. It covers what to buy or rent, how nodes connect, how Kubernetes or Slurm places work, and how to keep faulty hardware from wasting expensive hours.

The silicon and serving math live in GPU architecture and distributed training.

Read in order

StepConceptWhat it answers
1GPU hardware and interconnectsWhich memory, link and network does a job need?
2GPUs on KubernetesHow does a pod get a GPU, and how do you share one?
3Gang scheduling and Slurm vs KubernetesHow do you start all 32 workers together, or none?
4GPU failures and checkpointsWhat happens when a card fails mid-run?

Two products share the word GPU cluster

Training and inference want different things from the same hardware.

Training poolInference pool
AllocationExclusive or nearly exclusive nodesMany small replicas
SchedulingGang-scheduledFast scale-up
NetworkInfiniBand or RoCE, fast checkpoint storageTail latency and autoscaling matter most
PreemptionExpensive, since a killed job loses progressSpot works for stateless overflow
HardwareHomogeneous SKUs for predictable NCCL topologyMixed SKUs are fine if the router knows what runs where

Where capacity comes from

SourceStrengthTrade-off
Hyperscalers (AWS, GCP, Azure)Integrated IAM, storage and managed KubernetesQuota waits, price, and SKU availability varies by region
Neoclouds (CoreWeave, Lambda and similar)GPU-dense, often InfiniBand, sometimes lower cost per GPU-hourA different ops model with less of the full cloud
On-prem or colocationCapital control at high utilizationCapex, power, staffing and refresh cycles

In 2025 and 2026, quota and delivery timelines shape planning more than list price. Teams reserve capacity months ahead, or keep a second provider as an escape hatch.

Storage next to the GPUs

GPUs starve without data. Keep the object store as the source of truth, and cache active datasets and weights on node-local or rack-local NVMe. Otherwise every scale-up downloads 100+ GB of weights again. Pre-pull large CUDA images onto GPU nodes, because cold starts can dominate queue time.

Common mistakes across the topic

  • Ordering GPUs without asking the SKU, fabric and node size. "Eight H100s with IB" leaves too much open.
  • No checkpoints on a multi-day training run. One card failure then loses days.
  • Time-slicing for paying customers. It has weak isolation and noisy neighbors.
  • Unpinned drivers. A surprise driver upgrade in the middle of training is an outage.

Key takeaways

  • Choose GPUs by memory, interconnect and form factor, not by peak FLOPS.
  • Multi-node training needs RDMA fabric with enough bandwidth per GPU.
  • Kubernetes needs a device plugin, tainted GPU node pools, and MIG or time-slicing for packing.
  • Gang scheduling is mandatory for multi-GPU training.
  • Expect GPU failures, and make recovery routine with health checks and checkpoints.

Further learning

NVIDIA's GPU Operator docs are the practical install and upgrade path for Kubernetes clusters.

NVIDIA GPU Operator documentationAbout the NVIDIA GPU Operator — NVIDIA GPU Operatordocs.nvidia.com

The Hopper architecture deep dive explains HBM, Tensor Cores, NVLink and MIG at the level infra and ML engineers share.

NVIDIA Hopper Architecture In-DepthEverything you want to know about the new H100 GPU.NVIDIA Technical Blog

Google DeepMind's How to Scale Your Model is the clearest free book on parallelism and scaling laws for large models.

How to Scale Your Model (Google DeepMind)Training LLMs often feels like alchemy, but understanding and optimizing the performance of your models doesnHow To Scale Your Model