Colocation means putting servers you own into a data centre run by someone else. You keep the hardware. The provider runs everything around it: power, cooling, physical security and the connectivity that equipment needs to do its job.
A retailer might move its e-commerce servers out of a warehouse server room and into a rack at a colocation data centre. The servers stay theirs. The power infrastructure, cooling plant, site security and carrier relationships stop being their problem.
The colocation definition is plain: your hardware sits in someone else’s purpose-built data centre.
You buy and own the servers, switches and storage. You decide what to deploy and when to replace it. The provider supplies power, cooling, physical security and network access, then keeps that environment running.
Server colocation and colocation hosting describe the same arrangement. The distinction worth holding on to is ownership. With dedicated hosting, the provider owns the server and rents it to you. With colocation, the hardware is yours.
Space is sold as a few rack units, part of a rack, a full cabinet, a locked cage or a private suite. What you need depends on how much equipment you have, how much power it draws and how much physical separation you need to demonstrate.
Your equipment is installed in the facility and connected to the provider’s power and cooling. Connectivity comes from the provider, from third-party carriers through cross-connects, or through peering at an internet exchange.
Carrier-neutral facilities give you access to multiple networks instead of tying you to one. Some also offer private connections into public cloud platforms, so steady workloads can stay on owned hardware while cloud services handle the rest.
Remote hands covers the physical work your team cannot do from a desk two hundred miles away: rebooting equipment, swapping a failed drive, checking a status light, reseating a cable or racking kit that arrived on a pallet that morning.
Managed colocation goes further. Monitoring, patching and backup management move across to the provider. The hardware is still yours.
Two responsibilities separate cleanly here. You stay responsible for the IT equipment and everything running on it. The provider is responsible for the environment that equipment depends on.
That is the heart of what colocation means: control of your infrastructure without operating the building, power systems, cooling plant, physical security and carrier relationships around it.
| Area | Colocation | Dedicated server | Cloud hosting | Your own data centre |
|---|---|---|---|---|
| Hardware ownership | You own the servers | Provider owns the server | Provider owns the underlying infrastructure | You own everything |
| Facility responsibility | Provider manages power, cooling, security and the building | Provider manages hardware and facility | Provider manages the full infrastructure platform | You manage the entire facility |
| Control over hardware | High | Limited to the rented specification | Low at physical hardware level | High |
| Scaling | Requires hardware procurement, delivery, installation and available facility capacity. | Usually requires changing or adding rented servers | Capacity can be added quickly | Requires procurement and facility capacity |
| Upfront investment | Hardware plus setup and deployment costs | Little or no hardware capex | Pay-as-you-go operating model | High: construction, UPS, generators, cooling and security |
| Connectivity | Multiple carriers available in a carrier-neutral facility | Depends on provider | Built into the cloud platform | Procured and managed directly |
| Physical location | Known facility and rack location | Known provider facility | Depends on chosen cloud region and service | Fully controlled |
| Best fit | Owned hardware, predictable demand, hybrid estates and organisations that want facility resilience without operating the site | Organisations that want physical infrastructure without buying hardware | Variable workloads needing rapid scaling | Organisations with the sustained scale, in-house expertise and resources to design, build and manage both the facility and the IT it houses |
The benefits of colocation services come down to using infrastructure you would otherwise have to build and staff: redundant power, purpose-designed cooling, layered physical security, a choice of carriers and engineers on site.
Ownership comes with responsibility, and that applies to running your own data centre too, not just colocation. Set against dedicated servers or cloud hosting, a failed server power supply, an ageing server or a refresh cycle due next year stays with you, and scaling means ordering, waiting for and installing equipment yourself, a matter of weeks rather than minutes.
That responsibility has an upside, though. Ownership also means choosing precisely what hardware runs your workloads, from manufacturer to internal specification, rather than working within someone else’s configuration. That control is one of the clearer reasons organisations pick colocation over dedicated servers or cloud hosting in the first place.
What is colocation in cloud computing? It is best understood as the physical side of a hybrid estate. Colocation is not a type of cloud, and the two models do not have to compete.
Steady and business-critical workloads can run on owned hardware in the data centre, with private connections linking them to public cloud platforms for services that need more elastic capacity.
The result can be a hybrid IT strategy where the physical infrastructure remains under the organisation’s control while cloud services provide flexibility where it is useful.
Colocation makes sense when you have a reason to keep control of physical infrastructure and no good reason to run the building around it.
The signals are recognisable:
Hardware you have already paid for is one reason to use colocation. Performance, data location, cost predictability and infrastructure control can be others.
A colocation data centre is a facility built and operated to keep other organisations’ equipment running. Power architecture, cooling design, connectivity, security controls and the operational team behind them are all part of what you are buying.
Comparisons between UK colocation providers get useful when they get specific. Whether a facility describes itself as resilient tells you very little. How that resilience is designed, what evidence sits behind its security claims and who responds when something needs attention are questions that can actually be compared.
At Datum, the facility and the service around it are part of the same proposition. Farnborough and Manchester provide secure, carrier-neutral UK colocation, with service managers, operations teams and in-house engineers around the infrastructure.
Colocation space starts with the rack unit, or U: 44.45 mm of vertical space in a standard 19-inch rack. A full rack is commonly 42U, though larger cabinets are used.
Small deployments take part of a shared cabinet. A full rack gives one organisation the whole cabinet. Larger estates move into locked cages or private suites, where space and power are committed on a broader scale.
Having rack space for your equipment matters, but without sufficient power to support it, that space has little value.
Power density is quoted in kW per rack. Confirm the maximum supported density, whether that figure is a hard per-rack limit or an average across the hall, and how more power can be added as the estate changes. The gap between an average and a limit is where deployments can come unstuck.
Then ask whether the rack receives A and B feeds, how those paths are physically separated and what redundancy model sits behind them.
Cooling deserves the same treatment, and the vocabulary is shared. N means enough capacity for the current load, N+1 adds a spare, and 2N duplicates the system. Power and cooling can run different architectures, so ask about each one.
Hot and cold aisle containment controls airflow around equipment. The question worth asking is what happens to the environment when part of the cooling system fails.
Connectivity is one of the main reasons organisations move to colocation in the first place.
A carrier-neutral colocation facility lets you choose between network providers instead of accepting whichever one comes with the building. Resilience becomes easier to design, and changing carrier later becomes less of a project.
Ask for the current carrier list, not just the headline number. Then ask how the fibre enters the building. Two carriers sharing a duct still share a point of failure.
Cross-connects are the physical links between your rack and carrier equipment elsewhere in the facility. Internet access can come through IP transit or through peering at an internet exchange.
For hybrid strategies, private cloud connections can link colocated infrastructure directly into public cloud platforms without routing everything across the public internet.
Physical security works in layers: perimeter controls, security staff, CCTV, controlled doors, biometric or card access, visitor procedures, cabinet locks and segregated cages. Which of those apply at the specific site, and how they are operated day to day, is the part worth asking about.
Certifications are evidence of a different kind. ISO 27001 is earned through ongoing surveillance audits, not a one-off assessment, and covers information security management specifically. PCI DSS applies where payment card data is involved, and accreditations such as NSI Gold or PASF speak to physical security.
Always ask for the scope. A company-wide certificate does not automatically mean every facility sits inside it.
Where personal data is involved, UK GDPR responsibilities follow it. If the provider is acting as a processor, for example by handling backups under a managed service, the contract needs to reflect that. Where data residency requirements apply, the physical location of the data centre is part of the answer.
The people around the facility matter as much as the plant inside it.
Remote hands gives you engineers who can carry out physical work when your own team is not on site. Service management adds deployment planning, reporting, regular reviews and operational visibility.
Check what support is included, what is chargeable and how out-of-hours work is defined. Those details can vary significantly between providers.
At Datum, this layer is deliberate. The facility gives you the secure, resilient environment. The engineers, service managers and operations teams help plan the move, deploy the estate and keep the work visible once it is live.
Retail and wholesale colocation sit on the same underlying infrastructure but use different commercial models. Retail colocation covers smaller deployments, from partial racks to a number of full cabinets, with contracts built around cabinet space, power and associated services.
Wholesale colocation is for organisations taking much larger blocks of capacity, usually measured in committed power and dedicated areas rather than individual cabinets. Terms tend to run longer, and more of the fit-out or operational responsibility can sit with the customer.
The distinction is commercial. Both models still depend on the same questions around power, cooling, resilience, connectivity, security and support.
A colocation provider operates the facility and supplies the infrastructure and services around your equipment. Once your colocation requirements are clear, compare providers on evidence rather than broad claims.
Start with power: the allocation available to your rack, the redundancy architecture behind it and what happens when the requirement grows.
Then connectivity. Which carriers are present, whether they enter the building through physically separate routes and what private cloud connectivity is available.
Then security. Review the controls and certifications at the specific facility, and ask for certificate scope instead of relying on a provider-wide list.
Read the SLA properly. Check what availability commitment applies, how service credits work, whether they are capped, how faults are prioritised and whether a response target refers to acknowledgement or resolution. Those last two are not interchangeable.
Remote hands terms need the same attention: what the allowance covers, the billing increment once it runs out and what counts as out-of-hours work.
What is a colocation agreement? It is the contract covering the space, power and services you buy, along with the responsibilities on both sides.
Check contract length, termination notice, renewal terms and any mechanism for price increases. Responsibilities for access, hardware, support and managed services should be written down clearly.
A provider worth shortlisting should also be able to explain how deployment will work before your equipment arrives: goods-in procedures, rack preparation, cabling, access arrangements and engineering support on the day.
Finding a building with enough rack space is the easy part. What you are choosing is who supports the infrastructure and the people responsible for it.
Colocation pricing is built from several separate charges.
The base charge covers space, whether that is part of a rack, a full cabinet, a cage or a larger dedicated area. Power is billed separately, either on committed capacity or actual consumption.
Connectivity adds cross-connect charges, bandwidth and fees for specific carrier or cloud connections. Remote hands may include an allowance, with engineering time beyond it billed separately. Installation, rack preparation and cabling can also appear on the first invoice.
Wholesale colocation can lower the cost per unit of capacity in exchange for committing to more space or power, usually for longer.
So the headline rack price is a poor way to compare providers. Ask for an itemised quote showing space, power, connectivity, cross-connects, remote hands, installation and every other recurring or one-off charge separately. It should also be clear how those charges can change during the contract.
What a rack costs today is the smaller question. What matters is what the infrastructure, service and support will cost across the period you expect to use them.
There are numerous factors that can determine whether colocation is right for your estate, and none of them appear on a headline rack price. Power allocation tells you whether the hardware fits and what happens when it grows. Certificate scope tells you whether the compliance story holds for the specific site you are renting. An itemised quote tells you what the bill looks like in year two, once the included remote hands hours have gone and a second cross-connect has been added.
If you are weighing up colocation for business-critical IT, talk to us about your estate and what it actually needs from power, connectivity, security and service.