See Facebook's "Cold Storage" systems for an example of this https://code.facebook.com/posts/1433093613662262 https://code.facebook.com/posts/1433093613662262

See Facebook's "Cold Storage" systems for an example of this https://code.facebook.com/posts/1433093613662262 https://code.facebook.com/posts/1433093613662262 > To get the most data into this footprint, we needed high density, but we also needed to remain media-agnostic and low-frills. Using the theme that “less is more,” we started with the Open Vault OCP specification and made changes from there. The biggest change was allowing only one drive per tray to be powered on at a time. In fact, to ensure that a software bug doesn’t power all drives on by mistake and blow fuses in a data center, we updated the firmware in the drive controller to enforce this constraint. The machines could power up with no drives receiving any power whatsoever, leaving our software to then control their duty cycle. > Not having to power all those drives at the same time gave us even more room to increase efficiency. We reduced the number of fans per storage node from six to four, reduced the number of power shelves from three to one, and even reduced the number of power supplies in the shelf from seven to five. These server changes then meant that we could reduce the number of Open Rack bus bars from three to one.