Compute+storage: Existing single-layer Storage Spaces Direct clusters can be expanded by adding additional S2D nodes, which adds additional compute and storage resources to the shared pool.

Compute-only/Storage-only: When Storage Spaces Direct (S2D) is using the dual-layer deployment model, the storage nodes act as scale-out file servers and can be shared to any compute node through SMB3. Therefore the compute layer and the storage layer can scale-out independently.

The storage layer cannot be shared when Storage Spaces Direct (S2D) is using the single layer deployment model.