Some servers "stage" power on to disks. as spinning up disks is often the largest source of inrush current for e.g. a 10 disk server might only apply power to b

Some servers "stage" power on to disks. as spinning up disks is often the largest source of inrush current for e.g. a 10 disk server might only apply power to bays 2 at a time with a delay between each, this doesn't solve the inrush current problem of switching on a rack full or servers together (where managed PDUs come in)