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December 21, 2021

NFS Over RDMA Boosts Storage Performance

Last month, Dell Technologies’ Gregory Shiff, Principal Solutions Architect, Media & Entertainment published an interesting piece in IBC365 on network storage performance – if you have a (free) account it’s here. As it addresses the pain point we identified in last week’s piece on The Explorers, we bring you a summary here.

Shiff states that in 2021, storage can be a huge bottleneck – “working with native 8K video or high frame rate 4K video (60 frame per second+) is no joke.” This is especially the case with uncompressed media in real-time.

The article looks into using RDMA (Remote Direct Memory Access) for NFS (Network File System) storage traffic over Ethernet.

Schiff translates acronyms into English and explains that RDMA “allows for a client system to copy data from a storage server’s memory directly into that client’s memory”, and that NFS over TCP is the Linux way of addressing the most challenging storage situations.

RDMA’s direct communication increases throughput reducing latency and CPU load. The author describes and compares iWARP and RoCE with the latter being the winner for maximum storage performance with the lowest CPU load. “RDMA can be twice as performant as TCP all other things being equal (with a similar drop in workstation utilization).”

NFS Over RDMA Boosts Storage Performance
SOURCE IBC365 Read and write comparison for 50MB frames (simulating a 4K DCI resolution image sequence) and 190MB frames (simulating an 8K DCI resolution image sequence).

Schiff explains that without the need for real-time decompression, uncompressed 8K video puts less strain on workstations. There are, however, huge file sizes and bandwidth requirements. Using just TCP and test files of ~190 MB required 4.5 Gbps with 24 FPS playback, which simply didn’t work. “Mounting the exact same storage using RDMA was a night and day difference: 8K video at 24-frames per second over the network!”.

There are not yet that many cases where workflows will use totally uncompressed 8K video.

The article then looks at workstation performance, explaining how RDMA frees up cycles making them more versatile.

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