jtsoft
I suggest a send / receive buffer to let the hard disks turn off and rest, so these devices would turn on again when the buffer is full and needs to save the data inside to the hdds. The system will have to consider the queue and needs to load files waiting to upload into buffer as well as files that are downloading. When there is no file left to upload from the buffer or when there is no enough space to go on downloading into the buffer, the system would automatically reload the buffer.