RDMA-NDD(8)

📦 version 65.0, in alpine 3.24, arch rolling, centos-stream 10, centos-stream 9, debian bookworm, debian trixie, fedora 43, fedora 44, nixos 26.05, nixpkgs unstable, opensuse-leap 16.0, ubuntu jammy, ubuntu noble, ubuntu questing, ubuntu resolute, ubuntu stonking

💖 RDMA-NDD(8) — bestie edition 💖

okay so first thing, the vibe check: this is the manual page for RDMA-NDD, part of the OpenIB Diagnostics lineup. Pull up a chair, grab a strawberry 🍓, and let's get into it.

✨ NAME ✨

RDMA-NDD — the RDMA device Node Description update daemon 🦋

✨ SYNOPSIS ✨

rdma-ndd <options>

that's it, that's the whole summoning ritual 💅

✨ DESCRIPTION ✨

rdma-ndd is a system daemon, meaning it just chills in the background doing its little job forever. What's the job? It watches for changes to your rdma devices and/or changes to your hostname, and then updates the Node Description of the rdma devices based on whatever changed. Like a friend who notices you changed your profile pic and immediately updates the group chat nickname. no cap. 👑

✨ DETAILS ✨

For this daemon to do its full thing, you need kernels that support polling of the procfs hostname file, and you need libudev. Both. The whole package. 🎀

If your system doesn't support either of those features, it's not the end of the world — the daemon will just set the Node Descriptions at start up and then sleep forever. main character energy of a nap. 😴

🧚 Node Description configuration

The daemon reads the environment variable RDMA_NDD_ND_FORMAT to figure out what to set the node description to. And listen — you can drop wild cards in there for way more dynamic control:

  • %h — gets replaced with the current hostname (not including the domain, so keep your expectations realistic bestie)
  • %d — gets replaced with the device name (for example mlx4_0, qib0, etc.)

If you don't specify anything at all, the default is "%h %d". cute, sensible, iconic.

NOTE: At startup, and on new device detection, the Node Description is always written, so that the SM and rdma-ndd are in sync. Every subsequent event will only write the Node Description on a device if it has actually changed. no unnecessary writes, we respect the storage. 💀

🐧 Using systemd

Setting the environment variable for the daemon is normally done via a systemd drop in unit. For example, you could add the following to a file named /etc/systemd/system/rdma-ndd.service.d/nd-format.conf if you want to use only the hostname as your node description:

[Service] Environment="RDMA_NDD_ND_FORMAT=%%h"
NOTE: Systemd requires an extra '%'. yes, an extra one. do not fight it, just accept it. 😭

✨ OPTIONS ✨

  • -f, --foreground — Run in the foreground instead of as a daemon. For when you want to watch it happen live, like a livestream but for your node descriptions 🫶
  • -d, --debug — Log additional debugging information to syslog. for the girlies who need the receipts 🔍
  • --systemd — Enable systemd integration.

✨ AUTHOR ✨

Ira Weiny < ira.weiny@intel.com >

and that's the whole page babes 🌸 — brought to you by OpenIB Diagnostics, signed off on the RDMA-NDD(8) page itself. go update some node descriptions, you've got this 💜✨

📦 where this page comes from