A modular data centre is a complete small data centre built inside a shipping container or a similar steel box, with its own racks, power, cooling and network. It is also called a containerised data centre or a prefabricated data centre. It is built and tested in a factory, then delivered by truck to the site where it is needed.
Why put a data centre in a box? Some places produce large amounts of data but are far from any large data centre. A mine, an oil field, a port or an army camp may have no fibre cable at all. Sending all its data over a slow link to a distant city would take too long. So the computing is brought to the site instead. This is called edge computing.
Here is a typical case. An iron ore mine in Odisha runs 30 haul trucks, each with cameras and engine sensors. Together, they record several terabytes of video and readings every day. The nearest fibre cable is 60 km away, and the mine's only link to the outside world is a satellite connection of about 50 megabits per second. At that speed, sending one day's video would take days. So a modular data centre is set down beside the mine's office. Its servers run AI models that watch the video for drivers who look drowsy and for trucks that come too close to each other, and they raise an alert within a second or two. Each night, only the alerts, summaries and engine readings, a few gigabytes, go over satellite internet to the company's head office.
The container has everything that a large building has, on a smaller scale. It has a few racks, an air-conditioning or liquid cooling unit, a UPS, fire suppression and a locked door. Power comes from the site's own supply, often a diesel generator, or solar panels with batteries. Engineers in a distant city watch and repair the servers remotely, because nobody at the mine is trained to do it.
Some companies sell the box together with the computing inside it, for a yearly subscription fee. They also supply the satellite link and the software that runs the AI models. The buyer gets a small piece of the cloud in a place that the cloud cannot normally reach.
Modular data centres are also used where a building would take too long: to add space quickly beside an existing data centre, or to restore computing after a flood or a fire. A modular data centre differs from colocation, in which many companies rent space in one large shared building. A modular data centre usually serves one owner at one site.