What is Colocation Hosting?

The term 'colocation' refers to the locating of equipment in another location. Colocation hosting refers to clients who colocate their own server/s in another location - usually a high-quality data center.

The data center provides a space, a high-speed connection to the Internet, controlled air temperature, high security, high-redundancy, managed server solutions and more.

You'll see colocation spelt in various ways - colocation, co-location, collocation - all the same thing. Colocation hosting providers are either the data center owners themselves, companies who rent space in the data center, or colocation resellers who are not located on-site.

Colocating your own servers at a state-of-the art data center can offer many advantages. There are lots of things to consider - start-up costs, your business strategy, number of servers you wish to colocate, bandwidth providers, choosing the best data center location and a whole lot more.

Rack Space

A prime area to fully understand is 'rack space'. When/if you visit data centers, you'll see very similar setups. Servers are stored in cabinets on what are called 'racks'. Cabinets can be caged-off, locked, and/or grouped together in 'suites' depending on your needs.

Colocation providers charge you for the amount of 'rack space' your servers take up in their cabinets. The more 'rack space' you use, the more it'll cost you. Essentially, you are leasing 'rack space' from your provider for a monthly charge.

To determine how much 'rack space' is utilized, let's introduce the 'rack unit':

1 Rack Unit (1U) = 1.75" (1.75 inches high from top to bottom).

Standard rack equipment conforms to these units by being 1.75" high - or a multiple of that. Equipment is often stated in 'rack units'.

To find out how many rack units [U] you need, measure the height of the case and divide by 1.75. The more U need, the more space you require, thus a greater monthly cost.

1U = 1.75"
2U = 3.5"
3U = 5.25"
4U = 7"

Some typical-sized servers can be seen in the photos below:

1U Server (1.75" high):

2U Server (3.5" high):

4U Server (7" high):

When signing up for colocation space, you will have to specify how many 'rack units' you require. The cheapest option is a slimline 1U server. You should be given several options, EG: 1/4 cabinet, 1/2 cabinet, 3/4 cabinet, full cabinet, 1/2 cage, full cage and so on. The number of rack units in a 'full cabinet' varies between providers - but typically expect a full cabinet to be in the 40s Rack Units.

Some data centers have cabinets standing at over 7 feet tall (52 U +). They require a ladder or a very tall person to access the top servers.