Hard multi-tenancy is the architectural principle of providing strict, kernel-level isolation between tenants on shared infrastructure, ensuring no data leakage or performance interference. For GPU clusters in a sovereign AI cloud, this is non-negotiable for hosting competing enterprises or government agencies. Implementation requires a layered approach: physical GPU partitioning with technologies like NVIDIA Multi-Instance GPU (MIG), network segmentation with a service mesh like Istio, and storage quotas via a CSI driver. Each tenant's workloads, from training to inference, must run in fully isolated Kubernetes namespaces with dedicated resource guarantees.




