The rise of RDMA

I have known of RDMA (Remote Direct Memory Access) for quiet some time, but never in depth. But since my contract work ended last week, and I have some time off to do some personal development, I decided to look deeper into RDMA. Why RDMA?

In the past 1 year or so, RDMA has been appearing in my radar very frequently, and rightly so. The speedy development and adoption of NVMe (Non-Volatile Memory Express) have pushed All Flash Arrays into the next level. This pushes the I/O and the throughput performance bottlenecks away from the NVMe storage medium into the legacy world of SCSI.

Most network storage interfaces and protocols like SAS, SATA, iSCSI, Fibre Channel today still carry SCSI loads and would have to translate between NVMe and SCSI. NVMe-to-SCSI bridges have to be present to facilitate the translation.

In the slide below, shared at the Flash Memory Summit, there were numerous red boxes which laid out the SCSI connections and interfaces where SCSI-to-NVMe translation (and vice versa) would be required.

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Storage Facebook likes

There is a mini revolution going on, and Facebook is the main force driving it.

It is the Open Compute Project (OCP), and its mission is to redesign the modern-day data centers and drive open hardware and architectural designs and specifications, including storage. The overall goals are to drive greater data center efficiency, flexibility, energy savings and cost effectiveness in a new class of “hyperscale” datacenters. Facebook, Google and Amazon are some of the examples of hyperscale datacenters, where their businesses relies on massive computing power, exponential storage performance and racks and racks of computing infrastructure to drive their web-computing or cloud-computing services.

Some of the cool technology innovations in mind includes having systems that support any CPUs from any vendors including Intel and AMD. We may even see both processor brands running on the same motherboard. The Open Common Slots component for processors is based on PCIe. Intel has pledged their Decathlete motherboard specifications for OCP and likewise AMD has produced its Roadrunner mobo series specification for the project as well. The ARM processor could also be supported in the near future in this “mix-and-match” OCP ideals.

Other proposed changes include OpenRack specifications, “sleds”, and of course, the Open Vault project for storage (aka “Knox”). Continue reading