Survey on In‑Network Storage Systems

The article begins by describing the hardware architecture and performance characteristics of programmable network devices—including programmable switches and smart NICs—highlighting two primary challenges for high‑performance in‑network storage: the division of responsibilities between software and hardware, and system fault tolerance.

Based on the tasks performed by programmable devices (caching, coordination, scheduling, aggregation), existing in‑network storage systems are classified and analyzed. Representative examples such as NetCache, DistCache, NetChain, Concordia, Pegasus, Mind, NetLock, SwitchTx, and Xenic are examined, with tables summarizing their design trade‑offs, performance, and scalability.

The survey also discusses how programmable network hardware can accelerate various storage modules, significantly improving throughput and latency, while noting current limitations like single‑rack deployment, lack of multi‑tenant isolation, and security concerns for encrypted traffic.

Finally, the paper outlines four key research directions needed for broader adoption: (1) coordinated design of switches and NICs for comprehensive offloading, (2) efficient multi‑tenant support in cloud environments, (3) secure processing of encrypted data on programmable devices, and (4) automatic offloading of mature storage system components (e.g., Memcached, Ceph) to programmable network hardware.