S03 E13
8 May 2023/01:39:08

The Network Behind the Network

Bryan and Adam are joined by Oxide colleagues Arjen, Matt, John, and Nathaneal to talk about the management network--the brainstem of the Oxide Rack. Just as it ties together so many components, this episode ties together many many (many!) topics we've discussed in other episodes.

We've been hosting a live show weekly on Mondays at 5p for about an hour, and recording them all; here is the recording from May 8th 2023.

In addition to Bryan Cantrill and Adam Leventhal, we were joined by Oxide colleagues Arjen Roodselaar, Matt Keeter, John Gallagher, and Nathanael Huffman.

This built on work described in many previous episodes:

  • Cabling the Backplane Prior to going all-in on a cabled backplane with blind-mated server sleds (i.e. no plugging, unplugging, mis-plugging network cables). We (Bryan) espoused an "NC-SI or bust" mantra... at least in part to avoid doubling the cable count. With the cabled backplane, the reasons for NC-SI disappeared (which let the many reasons against truly shine).
  • The Pragmatism of Hubris in which we talk about our embedded operating system, Hubris (and it's companion debugger, Humility). Hubris runs on the service processors that are the main endpoints on the management network. Matt's work controlling the management network switch (the VSC7448) is in the context of Hubris, as is John's work communicating with the sleds over the management network.
  • The Power of Proto Boards showed and told about the many small boards we've used in development. Several of those were purpose built for controlling and simulating parts of the management network.
  • The Oxide Supply Chain Kate Hicks joined us to talk about the challenges of navigating the supply chain. Mentioned here in the context of "supply-chain-driven design": we designed around the parts we could procure! Tip: stay away from "automotive-quality" parts when the auto industry is soaking them all up.
  • Holistic Boot in which we talked about how (uniquely!) Oxide boots from nothing to its operating system and services. Over the management network, we can drive server recovery by piping in a RAMdisk over the network and then (slowly) through the UART to the CPU.
  • Get You a State Machine for Great Good Andrew joined us to talk about his work on a state-machine driven text-UI and its companion replay debugger. We mentioned this in the context of John replaying the long upload process in seconds rather than hours to fix a UI bug.
Major components of the management network

Matt's VSC7448 dev kit

Matt's remote tuning setup via webcam

Management network debugging

Management network debugging