Storage networking overview

Storage systems connect servers to disks and flash over a network. How that network is built decides which optical transceivers a storage fabric uses.

Block vs file

• Block storage presents raw volumes to a server, as if they were local disks. It runs over a SAN (Storage Area Network).
• File storage presents shares over the LAN — a NAS speaking NFS or SMB over IP.

SAN transports

• Fibre Channel — the classic dedicated SAN, lossless and low-latency (see Fibre Channel).
• IP storage — iSCSI and NVMe/TCP run over ordinary Ethernet.
• Converged — FCoE and NVMe-oF over RoCE carry storage on a lossless Ethernet fabric.

Optics

• FC SANs use FC-designated SFP+/SFP28 modules (SW/LW).
• IP and converged storage use Ethernet optics — 10/25/100G and beyond.

The exact protocols and the optics they use are covered in Storage protocols & optics.

Whatever the transport, CodingBox reads and codes the same transceiver memory, so a module presents the right identity to a storage switch.

Further reading

• NVMe over Fabrics — FC-NVMe, NVMe/TCP, NVMe/RoCE and NVMe/IB compared; what each asks of the links and optics.
• Lossless Ethernet for storage — DCB, PFC, ETS, DCBX, ECN/DCQCN, PFC storms and deadlocks, iSCSI practice, physical-layer requirements.