NVMe/TCP vs NFS

Block vs. File: Different Access Models

NVMe/TCP and NFS are not competing for the same workloads in the way that NVMe/TCP and iSCSI are. They operate at fundamentally different layers of the storage stack, which means the comparison is less about which is "better" and more about which access model matches what your application actually needs. Understanding this distinction up front saves a significant amount of architectural confusion.

NVMe/TCP presents a raw block device to the host. From the operating system's perspective, an NVMe/TCP volume looks identical to a locally attached NVMe SSD — a sequence of addressable sectors with no inherent structure. The host formats it with whatever filesystem it chooses (ext4, XFS, ZFS, or none at all for databases that do raw I/O), mounts it, and owns it exclusively. This exclusivity is the key trade-off: a block volume is attached to exactly one host at a time, which means the host takes full ownership of caching, write ordering, and crash consistency. The reward for that exclusivity is performance — block I/O operates without the overhead of a network filesystem protocol, delivering latency in the tens-of-microseconds range.

NFS presents a POSIX filesystem that multiple clients can access simultaneously over the network. The NFS server handles locking, cache coherency, and concurrent writes across all connected clients. This shared-access model is genuinely valuable for workloads where multiple machines need to read and write the same file namespace — distributed build systems, shared ML training datasets accessed by many GPU nodes at once, or media production environments where editors on different workstations collaborate on the same project directory. The latency cost is significant (500 µs to several milliseconds versus 25–40 µs for block) because NFS must serialize and arbitrate concurrent access and carry the weight of the VFS layer over the network. For workloads that don't need shared access, that overhead buys nothing.

Use Case Matrix

Can You Use Both?

Absolutely — and many organizations should. NFS and NVMe/TCP address different layers of the storage hierarchy, and a well-designed infrastructure commonly uses both simultaneously. A typical pattern in a Kubernetes-heavy environment is: NVMe/TCP block volumes for stateful workloads that own their data (databases, message queues, time-series stores) and NFS for shared datasets, configuration files, or large artifact stores that multiple pods need to read concurrently. The two protocols coexist on the same Ethernet fabric without conflict. Treating them as mutually exclusive leads to either under-provisioning performance for block workloads or over-engineering the architecture for shared-access scenarios that a simple NFS mount handles perfectly well.

The practical decision tree is straightforward: if a workload needs exclusive, low-latency block I/O — a database, a VM image, a Kubernetes PVC for a stateful microservice — choose NVMe/TCP. If a workload needs concurrent file access across multiple clients — a shared dataset, a build artifact cache, a home directory server — choose NFS. The protocols are complementary, not competing.

Conclusion

The NVMe/TCP vs NFS decision is, at its core, a question about your workload's access pattern: exclusive block I/O or shared file access. For high-performance, latency-sensitive workloads where a single host owns the storage, NVMe/TCP delivers transformative performance improvements over NFS. For shared access use cases, NFS remains the pragmatic and proven choice. For teams running Kubernetes who need fast, dedicated block storage for their stateful applications, simplyblock.io provides NVMe/TCP persistent volumes with a CSI driver that provisions and manages block storage natively within the Kubernetes control plane.