A server that is not a PC

Today, servers are PCs. They have the same architecture as PCs. They run PC operating systems. But do they have to be PCs? Is there another approach? There might be.

First, let's consider PCs. PCs have lots of parts, from processor to memory to storage, but the one thing that makes a PC a PC is the video. PCs use memory-mapped video. They dedicate a portion of memory to video display. (Today, the dedicated memory is a "window" into the much larger memory on the video card.)

Which is a waste, as servers do not display video. (Virtual machines on servers do display video, but it is all a game of re-assigned memory. If you attach a display to a server, it does not show the virtual desktop.)

Suppose we made a server that did not dedicate this memory to video. Suppose we created a new architecture for servers, an architecture that is exactly like the servers today, but with no memory reserved for video and no video card.

Such a change creates two challenges: installing an operating system and the requirements of the operating system.

First, we need a way to install an operating system (or a hypervisor that will run guest operating systems). Today, the process is simple: attach a keyboard and display to the server, plug in a bootable USB memory stick, and install the operating system. The boot ROM and the installer program both use the keyboard and display to communicate with the user.

In our new design, they cannot use a keyboard and display. (The keyboard would be possible, but the server has no video circuitry.)

My first though was to use a terminal and attach it to a USB port. A terminal contains the circuitry for a keyboard and display; it has the video board. But no such devices exist nowadays (outside of museums and basements) and asking someone to manufacture them would be a big ask. I suppose one could use a tiny computer such as a Raspberry Pi, with a terminal emulator program. But that solution is merely a throwback to the pre-PC days.

A second idea is to change the server boot ROM. Instead of presenting messages on a video display, and accepting input from a keyboard, the server could run a small web server and accept requests from the network port. (A server is guaranteed to have a network port.)

The boot program could run a web server, just as network routers allow configuration with built-in web servers. When installing a new server, one can simply attach it to your network and then connect to it via SSH.

Which brings us to the next challenge: an operating system. (Or a hypervisor.)

Today, servers run PC operating systems. Hypervisors (such as Microsoft's Hyper-V) are nothing more than standard PC operating systems that have been tweaked to support guest operating systems. As such, they expect to find a video card.

Since our server does not have a video card, these hypervisors will not work properly (if at all). They will have to be tweaked again to run without a video card. (Which should be somewhat easy, as hypervisors do not use the video card for their normal operation.)

Guest operating systems may be standard, unmodified PC operating systems. They want to see a video card, but the hypervisor provides virtualized video cards, one for each instance of a guest operating system. The guest operating systems never see the real video card, and don't need to know that one is present -- or not.

What's the benefit? A simpler architecture. Servers don't need video cards, and in my opinion, shouldn't have them.

Which would, according to my "a PC must have memory-mapped video" rule, make servers different from PCs. Which I think we want.

The video-less server is an idea, and I suspect that it will remain an idea. Implementing it requires special hardware (a PC minus the video circuitry that it normally has) and special software (an operating system that doesn't demand a video card) and special boot ROM (one that talks over SSH). As long as PCs are dominant, our servers will simply be PCs with no display attached.

But if the market changes, and PCs lose their dominance, then perhaps one day we will see servers without video cards.