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fan-control: estimate + expose fan power (fan_watts_est)

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The iDRAC reports only total DCMI watts + RPM (no per-fan power), so add a
cube-law fan-power estimate: fan_W ~= 0.0205*(RPM/1000)^3, calibrated to the
2026-06-05 sweep (fits within ~3W; ~2W floor -> ~99W full). The daemon reads
live RPM each loop and pushes pve_fan_control_fan_rpm + _fan_watts_est.
Surfaced in HA as sensor.r730_fan_power_est + a "Fan Power (est)" card on the
dashboard-it Server view, next to total power. 46 bash tests green; verified
live (9120rpm -> ~15W est).

[ci skip]

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
Viktor Barzin 2026-06-05 11:10:27 +00:00
parent 324f2dc3bf
commit 51456a96f6
4 changed files with 41 additions and 7 deletions
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17
docs/plans/2026-06-04-pve-fan-control-design.md
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@ -103,10 +103,19 @@ Manual fan mode bypasses the iDRAC's own protection, so it is backstopped:
## Observability
Pushes to the existing Pushgateway (`http://10.0.20.100:30091`, job
`fan_control`): `pve_fan_control_cpu_temp_celsius`, `_fan_percent`, `_mode`
(1 quiet / 2 cool / 0 fallback), `_ha_reachable`, `_fallback`. The existing CPU-
temp alert is unaffected.
Pushes to the Pushgateway (`http://10.0.20.100:30091`, job `fan_control`):
`pve_fan_control_cpu_temp_celsius`, `_fan_percent`, `_mode` (1 quiet / 2 cool /
3 manual / 0 fallback), `_ha_reachable`, `_fallback`, `_fan_rpm`, and
`_fan_watts_est`.
**Fan power is ESTIMATED** — the iDRAC exposes only total DCMI watts + RPM (no
per-fan power), so `_fan_watts_est` models it from RPM via the fan affinity law
(power ∝ RPM³), calibrated to the 2026-06-05 sweep: `fan_W ≈ 0.0205·(RPM/1000)³`
(≈2 W at the floor → ~99 W at full; fits the sweep within ~3 W). Surfaced in HA
as `sensor.r730_fan_power_est` + a "Fan Power (est)" card on the dashboard-it
Server view, next to total power (`sensor.r730_power_consumption`, redfish) — so
the fan tax of the control curve is visible. The existing CPU-temp alert is
unaffected.
## Testing

5
docs/runbooks/fan-control.md
View file

@ -24,7 +24,10 @@ can't run the fans wrong indefinitely. `CEILING` (83 °C) still overrides
everything → Dell auto. An HA change is applied within one daemon loop (~15 s).
Monitoring sensors on the same view: `sensor.r730_fan_speed` (redfish exporter),
`sensor.r730_fan_control_target` + `sensor.r730_fan_control_mode` (Pushgateway).
`sensor.r730_fan_control_target` + `sensor.r730_fan_control_mode` +
`sensor.r730_fan_power_est` (Pushgateway). `r730_fan_power_est` is an ESTIMATE of
total fan power (the iDRAC reports no per-fan power) — modelled from RPM via the
fan affinity law (∝ RPM³), calibrated to the power sweep (~2 W floor → ~99 W full).
The HA objects (helpers, the auto-revert automation, the REST sensors in
`rest_resources/{idrac_redfish_exporter,fan_control}.yaml`, and the dashboard