Powering a GPU Node On-Demand with iDRAC and Redfish

Wed, 15 Apr 2026 00:00:00 +0000

There’s a Dell PowerEdge R630 in my homelab whose only job is GPU work — mainly Ollama for self-hosted LLM inference. Rack servers are power-hungry, and paying to idle one 24/7 for something I use a few hours a week is absurd. So the machine stays off by default and boots on demand.

Redfish: the API your server already has

Every server with a BMC (iDRAC on Dell, iLO on HP) exposes the Redfish API — a REST interface to the hardware itself. The BMC draws a couple of watts and is always reachable, even when the host is powered off. Power control is a single POST:

curl -sk -K ~/.bmc-creds \
 -H 'Content-Type: application/json' \
 -X POST "https://$BMC/redfish/v1/Systems/System.Embedded.1/Actions/ComputerSystem.Reset" \
 -d '{"ResetType": "On"}'

Two details worth stealing:

Keep credentials out of argv. Curl’s -K flag reads options from a file, so the BMC password never shows up in ps or shell history. The creds file is chmod 600, owned by root.
GracefulShutdown first, ForceOff as the escape hatch. Redfish supports both; the graceful path lets the OS unmount cleanly.

I wrapped this in a ~40-line script (esxi up | down | status) that also queries PowerState, so any machine on my VPN can check or change the server’s state in one command.

Making it a button

CLI is fine at a desk, but the whole point is “I want to ask a model something now.” So the script is wired into a small dashboard on my hypervisor — one page showing every service’s health, with Power on / Shut down buttons for the GPU node. Boot to Ollama-ready takes about four minutes; the dashboard’s status dot flips green when the tunnel to it comes back up.

The pattern generalizes to anything with a BMC:

State lives in the BMC, not the OS — you can always trust it.
Actions are idempotent Redfish POSTs — safe to put behind a button.
Health is best checked end-to-end — I probe the actual Ollama endpoint, not just a ping.

The economics

An R630 idles around 90–120 W. At my rates, leaving it on costs roughly $10–15/month to do nothing; on-demand it’s pennies. The four-minute boot is a fair trade for inference that runs on my hardware, on my network, with no tokens metered by anyone.

Bash | Sergio Saucedo

Powering a GPU Node On-Demand with iDRAC and Redfish

Redfish: the API your server already has

Making it a button

The economics