Power — PDU and UPS
How the rack is fed: one metered, switchable PDU on the external side of the rack and a 2 kVA UPS at the bottom that covers rumba only. Live readings are on the rack status page; the room's thermal history is in the incident log.
PDU
| Model | APC NetShelter Rack PDU 2G, metered-by-outlet with switching (AP8681) |
| Capacity | 11 kW — 230 V three-phase input, 21× C13 + 3× C19 outlets |
| Management | 192.168.88.10 — web UI, SSH, SNMP (public, read-only); admin credentials in the secretzone. Reachable from inside 192.168.88.0/24 only: from a VPN client the device answers ICMP but not SNMP, HTTP or HTTPS (tested 2026-08-13). In-rack pollers are unaffected |
| Firmware | NMC AOS/app v6.9.6, hardware rev 02 (manufactured July 2021) |
| Environment probe | Temperature/humidity sensor attached — 26.2 °C / 46 % RH in July 2026; alarms at 45 °C high / 50 °C max, 1 °C hysteresis |
| Alarm email | Since 2026-08-10, threshold events are emailed through the rack relay (recipient 1, route local) — configured by provisioning/mail/pdu-email.sh |
Load measured in July 2026: 1.1 kW total (2.8 / 2.2 / 0.6 A per phase at ~241 V), peak 3.6 kW and 10.5 MWh accumulated since the energy counter reset in November 2025. Phase L3 carries almost nothing — worth considering when plugging in new machines.
Each outlet is individually metered and switchable, so a hung machine can be power-cycled remotely from the PDU web UI.
The room overheated around June 22–23, 2026 — the probe recorded up to 76.4 °C and no machine shut down automatically. Full account in the incident log; a layered protection policy is proposed in Thermal protection & emergency shutdown.
UPS
A BlueWalker VFI 2000 RMG PF1 (2 kVA, online double-conversion) sits at the bottom of the rack at U2–3. Read over its USB link in August 2026:
| Management | No network interface. USB only — cabled to rumba since 2026-08-03, where it appears as USB HID 0665:5161 (OLHV2K0, serial 83222109100407) |
| State | Healthy and on mains — charging, AC present, no fault or replace-battery flag; battery at float (82.0 V on 72.0 V nominal = 13.67 V/cell) |
| Protects | rumba, both PSUs — cords moved 2026-08-03. Nothing else |
| Load | 14 % — ~1.0 A / 265 W, matching rumba's own draw |
| Input / output | 244 V in, 229.5 V out. Its own input comes from the PDU, so the rack total is unchanged |
The load is live on the rack status page, which also raises a Telegram alert if mains is lost. Nothing per-outlet is available: the UPS has no switchable load groups.
At 14 % the unit has plenty of headroom for rumba alone, but it could never carry the rack: the PDU recorded a 3.63 kW peak during the June 2026 heat event against ~1.10 kW at rest. Anything more that should ride through a power cut — the NAS holds the only copy of the student homes — has to be chosen deliberately, and that is an open item in the todo.
Two things make cord tracing a desk-unfriendly job, which is why renaming the 24 factory-default PDU outlet names is an open item: iDRAC reports PSU input voltage in ~8 V steps (it read a flat 240.0 V on both PSUs before the move and 232 V after, close to but not equal to the UPS's measured 229.5 V), and a PSU's standby draw sits below the UPS's measurement floor.
The driver, the full variable list and the shutdown policy are on the UPS monitoring page.