New-Tech Europe Magazine | Sep 2019 | Digital Edition

b. NVMe-over-iWARP (NVMe/ iWARP) - The iWARP RDMA protocol runs on standard TCP/IP networks, and is therefore much more straightforward to deploy. Though its latency is not quite as good as RoCE’s, its greater ease of use and much lower administration overheads are very appealing. At this stage, storage array vendors are not designing arrays to support iWARP, so iWARP is for the moment best suited for software-defined or HCI solutions like Microsoft Azure Stack HCI / Storage Spaces Direct (S2D). 3. NVMe-over-TCP (NVMe/TCP) NVMe-over-TCP is the new kid on the block. Ratified in November of 2018, it runs on existing Ethernet infrastructure with no changes necessary (taking advantage of the incredible pervasiveness of TCP/ IP). The performance that NVMe- over-TCP delivers may not be quite as fast as NVMe-over-RDMA or FC-NVMe, but it can be easily implemented on standard NICs and network switches. The key benefits of NVMe SSD storage can still be derived without requiring significant hardware investment. Some NICs like the Marvell® FastLinQ ® 10/25/50/100GbE have the potential to offload and

are two different types of RDMA implementation – namely RDMA- over-converged-Ethernet (RoCE) and Internet wide-area RDMA protocol (iWARP). These protocols are unfortunately not interoperable with one another. We'll now briefly explain the respective benefits of each: a. NVMe-over-RoCE (NVMe/ RoCE) - When using Ethernet only networks, NVMe-over-RoCE is a good choice for shared storage or hyper-converged infrastructure (HCI) connectivity. Consequently, many storage array vendors have announced plans to support NVMe-over- RoCE connectivity. RoCE provides the lowest Ethernet latency and works well when the storage network involved is of a small scale, with no more than 2 hops. As the name implies, RoCE requires a converged or lossless Ethernet network to function. This approach enables extra network capabilities including data center bridging, priority flow control, plus more complex setup and network management mechanisms. If low latency is the overriding goal, then NVMe- over-RoCE is likely to be the best option, despite the heightened network complexity.

accelerate NVMe/TCP by leveraging built-in capabilities of offloading the TCP/IP stack in the NIC.

Summary

Whichever NVMe-over-Fabrics route you decide to undertake, Marvell offers a flexible portfolio and can offer any assistance in the implementation process. In particular, the Marvell QLogic ® 16Gb and 32Gb FC host bus adapters support FC-NVMe, and (thanks to the Universal RDMA feature incorporated) the Marvell FastLinQ 41000 and 45000 series of 10/25/40/50/100Gb Ethernet NICs and converged network adapters support both NVMe-over-RoCE and NVMe-over-iWARP functionality, as well as NVMe-over-TCP. Accordingly, administrators can architect their systems based on their needs, while being assured that what they deploy today will be future-proofed for the networks of tomorrow. by DRAMeXchange and other industry analyst sources *Per data published

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