Mt. Diablo is a disaggregated power rack infrastructure being developed by Meta, Microsoft, and Google to address the needs for racks with over 500 kW of power such as Kyber.
The concept is to have a single “sidecar” rack full of power shelves (rectifiers) which convert the datacenter’s AC power into DC. This sidecar then delivers DC directly to one or more racks in the same row via a high-voltage DC busbar, eliminating the need for power supplies in individual servers or power shelves in the same racks as servers. This allows more servers to be shoved into a single rack, meaning more compute is within the reach of low-cost copper interconnects such as NVLink.
It proposes moving from 48 VDC to 400 VDC,1 and designs include +/- 400 VDC that enable up to 1 MW per rack.2
Competing standards
Interestingly, Mt. Diablo is different from NVIDIA’s proposed 800 VDC architecture3 despite both supporting 800 V. Mt. Diablo is a sidecar power rack, whereas NVIDIA’s proposal is to do row-scale 800 VDC instead of row-scale 415/480VAC.