Hardware-software disaggregation

Hardware-software disaggregation means buying a piece of equipment's hardware and its software separately, often from different companies, instead of as one sealed box. For decades, a mobile tower's radio, a data-centre switch, an office phone system or a storage array came from one maker, which supplied the box and the software inside it together. Disaggregation pulls the software off the box, so that it can run on ordinary hardware.

Here is how it works in general. First, companies agree on a common standard for how the hardware and the software connect. Hardware makers then build plain, general-purpose equipment to that standard. Often this is an ordinary server, or a white-box switch, which is a switch sold without a brand's own software. A separate company writes the software that runs on it. The buyer chooses each one, and can later replace either one without replacing the other. The software is often sold as a subscription and updated like any other app.

Why do buyers want this? A sealed box ties the buyer to one maker for the life of the equipment, which is called vendor lock-in. Plain hardware costs less, because many makers compete to build it. And new features arrive as software updates, not as new boxes. The cost is that the buyer, or a system integrator, must make the pieces work together. When something breaks, it is also less clear which company must fix it.

Take, for example, a large cloud company's data centre. It buys plain switches and runs a separate network operating system on them, such as SONiC, as described in white-box networking.

Consider an office that once kept a telephone switch in a cupboard. The office phone system (PBX) has become software, now sold as a cloud phone system that runs on the provider's servers.

Say a company needs more storage for its files. Software-defined storage turns ordinary servers full of disks into a storage array, instead of a sealed box from one storage maker.

The best-known case is the mobile tower. Open RAN lets an operator buy the tower's radio from one company and the software that runs it from another.

How is disaggregation different from virtualisation? Virtualisation splits one physical server into many pretend computers, called virtual machines. Disaggregation is about who supplies the software and who supplies the hardware. The two often go together, because disaggregated software frequently runs inside virtual machines or containers on ordinary servers.