This was a feature on SCSI disk controllers. I remember one controller that had dip switches to set the spin up sequence number, and then you would configure the controller to wait for all the drives to be spinning before it tried to bring the array online.

I'm going from memory here but each Ultra 320 SCSI HDD had a startup current of almost 2 Amps so if you had a disk shelf with 24 drives and stack a few shelves in each rack you could do some serious power damage if you didn't plan the startup sequence right.