What Is Colocation?
Colocation is one of the most useful — and least understood — options in IT infrastructure. This guide explains what it is, how it works, and how to judge a good facility, without the jargon.
If you run servers, you have three basic choices about where they live. You can keep them in your own building (on-premise). You can rent computing from someone else entirely (the public cloud). Or you can own the hardware but house it in a professional data center built for the job. That third option is colocation — and for a great many businesses, it is the most pragmatic of the three.
Despite being a foundational part of the internet, colocation is rarely explained clearly. Let us fix that.
Colocation, defined
Colocation — often shortened to "colo" — is the practice of placing your own servers and networking equipment in a third-party data center. You own and control the hardware; the facility provides the building, the power, the cooling, the physical security and the network connectivity that the hardware needs to run reliably. You rent space — measured in rack units, full racks or cages — along with the power and bandwidth to match.
Think of it like a high-security, climate-controlled garage for your most important machines. You own the cars; the facility provides the building, the guards, the power and the road access — all engineered to a standard almost no individual company could justify building for itself.
Why not just keep servers in the office?
Running serious hardware in a normal building is harder than it looks. Servers need clean, uninterrupted power; they generate heat that must be removed continuously; they need fast, redundant network connections; and they need physical security and fire protection. Replicating all of that in an office — with the redundancy to survive a power cut or a failed air-conditioner — is expensive and rarely done well.
A data center exists precisely to provide these things at a scale and reliability that make sense only when shared across many tenants. The result is far higher uptime, efficiency and security than almost any on-premise setup can match.
Why not just use the cloud?
The cloud is excellent, but it is not always the right answer. Owning your hardware can be substantially cheaper for steady, predictable workloads. It gives you complete control over the exact equipment you run — important for specialised needs like GPU servers, particular storage configurations, or compliance requirements. And it keeps your data on machines you physically own, in a location you choose. Colocation lets you have that ownership and control without taking on the impossible job of running a data center yourself.
Colocation is the middle path: the control and economics of owning your hardware, with the reliability and security of a professional facility — and none of the burden of building one.
What to look for in a colocation facility
Not all data centers are equal. A handful of factors separate a good one from the rest.
Power and redundancy
Look for redundant power feeds (often described as 2N or N+1), uninterruptible power supplies, and backup generators with a meaningful fuel reserve. Tier ratings (Tier III and above) are a useful shorthand for how much redundancy is built in, and they translate directly into uptime — the best facilities target availability above 99.99%.
Cooling and efficiency
Efficient cooling keeps your hardware healthy and your costs down. A facility's PUE (Power Usage Effectiveness) measures how much energy goes to computing versus overhead; lower is better, and a figure well under the industry average of around 1.57 signals a modern, efficient site. For AI and GPU workloads, ask whether the facility is ready for high-density and liquid cooling.
Connectivity
A good colocation site is carrier-neutral — meaning you can choose among multiple network providers rather than being locked to one — and offers high-bandwidth, redundant connections. Proximity to a major internet exchange (in Germany, the DE-CIX in Frankfurt) means lower latency and better routing.
Security
Expect 24/7 monitoring, multi-factor access control, video surveillance and fire detection and suppression. Your hardware should be physically protected as well as electrically and environmentally.
Sustainability
Increasingly important — and increasingly a differentiator. Facilities powered by renewable energy, with on-site solar and no water consumption for cooling, let you run your infrastructure with a far smaller footprint.
The Frankfurt advantage
The Frankfurt/Rhine-Main region is one of the world's premier data-center hubs, home to the DE-CIX internet exchange and exceptional connectivity. Colocating here means low latency to the rest of Europe and access to first-class, efficient facilities.
Who is colocation for?
Colocation suits any organisation that wants to own and control its hardware without operating a data center: companies with steady, predictable workloads where ownership is cheaper than renting; those with specific compliance or data-residency needs; and increasingly, businesses deploying GPU servers for AI that want dedicated, efficient, well-connected homes for that hardware. It is also a natural fit alongside private AI infrastructure — your model, on your server, in a facility you can point to on a map.
The bottom line
Colocation is the quiet workhorse of modern infrastructure: you keep the ownership and control of your own hardware, and a professional facility provides the power, cooling, connectivity and security that make it reliable. For steady workloads, compliance-sensitive data and GPU-heavy AI, it is often the most sensible option of all — and through Euner, businesses can access high-availability colocation in the Frankfurt region without navigating it alone.