We have a large maintenance this weekend as the electricians cutover power to a several hundred AMP 480V switch panel in preparation for bringing a large 675KW UPS online. Also, at the same time, they lumped in some plumbing work to cutover to the 14" chilled water mains. So, in order to avoid any sort of inrush issues, we're shutting down the 588 machines in the cluster.

The current measurement units on the Starline 400A buses still read between 20A and 28A after shutdown, which means that this power is divided among 50 24 port Voltaire switches, 2 288 port Voltaire switches, 20 HP 10/100 ProCurve 2600 series switches, 22 Force 10 S50N switches, and 2 Force 10 S2410 switches, as well as whatever inefficiency exists in powering 30 Servertech 60A CDUs, 4 30A 0U PDUS, 10 30A 2U PDUs (all of which have monitoring hardware on board), and a Cyclades ACS 48 port console server. That's a fair bit more current than I would have intuited, and a fair percentage of a medium loaded cluster consuming about 160 A per phase at 208V (3 phase).

But, it's enough to just shutdown the compute servers to prevent a substantial amount of inrush when everything comes back on early on Monday morning.