RDMA: The Reason Remote Storage Feels Like It's Plugged Into Your Motherboard
Your SSD does 4K reads in 80 microseconds. Your network stack just added 150 µs. That was the whole problem — until RDMA removed the network from the latency math.
The bottleneck nobody talks about
For most of the 2010s, the rule was simple: if you wanted fast storage, you kept it local. NVMe SSDs kept getting faster — 4K random reads in the tens of microseconds — while the network path stayed stubbornly expensive. Every byte pushed to a remote drive had to survive the kernel network stack: socket buffers, interrupts, context switches, multiple memory copies between user space and the kernel. The network didn't just add latency; it burned CPU — 2 to 4 cores per million IOPS in software, just to move data around.
Remote Direct Memory Access (RDMA) is what broke this trade-off. It lets one computer read and write another computer's memory directly, with no...
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