Guide to UK colocation

Overview

Colocation is a service where you place your own web server and network equipment in an Internet data centre, or colocation facility. But there are far more criteria to consider with this option than simply the cost of buying the server and the monthly fee charged by the hosting company.

Usually, the server owner will deal with the data centre through a hosting company such as Intrahost. Hosting companies situate their own servers and colocated servers in the same racks in the data centres.

Your hosting company, like Intrahost, will deal with the data centre on your behalf. The data centre will be responsible for providing your server with a reliable high speed connection to the Internet, uninterruptible power supply, air conditioning and physical security from fire and theft.  There are different standards of data centre in the UK, referred to as “Tiers”. Only Tier 2 data centres and above have redundancy for power, telecoms and air conditioning which gives them a greater capacity to continue working in the aftermath of a major event e.g. major electrical blackout in the vicinity of the data centre. The data centre you end up in will usually be directly related to your choice of web hosting company. Although a few hosts, like Intrahost, do offer you a choice of data centre, so that you may pick one close to you geographically that will make visiting your server easier. Physical access to your server is usually 24 hours a day.

Choosing colocation enables you to choose your own brand and specification of web server rather than one offered by your choice of hosting company. Dell rather than HP? It’s your call.

You will have to have staff capable of running the server, installing software, security updates, physically replacing malfunctioning parts eg disk drive, or adding more RAM. You will have to have someone on call 24/7. It is possible to outsource this function but it is a cost to be borne in mind when calculating the cost of your colocated server.

Cost of colocation

One of the drawbacks of colocation is the cost, much of it upfront before you are even online. A new web server can cost over a thousand pounds, and if you choose a second-hand server they will not be as fast as the latest dedicated servers offered by your hosting company, they will use more power (see below), they can be physically larger (see below) and you may still have to pay for updated software.

Additionally, you will have to pay the hosting company a monthly fee for rackspace in the data centre and for the bandwidth used by your server which is sometimes also referred to as “traffic”.

Anyone used to hosting a domain on a shared web server (as millions do), or even running a virtual dedicated server can be thrown when trying to work out the monthly cost of colocating a web server.

With shared web hosting monthly costs largely depends on size of disk space offered and total bandwidth available to be used by the user’s traffic over the month. e.g 250GB HDD plus 2000GB bandwidth. With virtual or dedicated servers the configuration of the server (CPU, RAM etc) usually factors into the price along with disk space and monthly traffic as before.

However, with colocation the configuration of the server is irrelevant as you are providing it and that includes the disk space. Traffic or bandwidth is relevant to cost but calculated in a different way.

With colocation it is rackspace used (or power used whichever is greater) plus bandwidth that determines your ongoing monthly costs.

However, with colocation bandwidth can have two meanings depending on which host you use. The one used by your colocation host can mean a huge difference in the price you pay per month and on your ability to budget for your web hosting costs.

There are two methods of measuring and charging for colocation bandwidth.

Firstly, capped bandwidth (or unmetered transfer), which is the method chosen by Intrahost. With this method the total amount of traffic or bandwidth used in a month is irrelevant. This is because you pay a fixed amount each month for a fixed amount of bandwidth that is available to your server per second e.g. 1 Mbps. This means that your server can handle up to 1 Mb of data each and every second. That figure is capped at whatever you have chosen and cannot be increased to cope with a sudden surge in demand. However, your server’s logs will indicate to you if demand is such that you need to increase your capped bandwidth to, say, 2Mbps.

Secondly, we have the real data transfer method; this involves paying for the total amount of traffic used by your server each month. While that might sound fair you have no idea how popular your server is going to be in the future, what if a domain is mentioned on TV or a video becomes a YouTube hit and thousands of downloads occur; you may find yourself hit with a huge monthly bill and so it is impossible to budget properly using this method. On the positive side this sort of burstable bandwidth does allow your server to cope with a sudden, unexpectedly high demand that may be caused by the appearance of an advert, news story or the release of a product without the server appearing to the end-user to be slowing down.

So, clearly bandwidth usage is going to be a major factor in your monthly cost but there are two other elements to consider.

Firstly, the amount of rackspace required by your server, because a data centre only has a finite amount of space in which to house web servers. A data centre provides metal racks with bays in which to house your servers. A rack can hold up to 42U of servers. The U is a unit of measurement. The vertical space used by a server is measured in Rack Units or U-Space; each U equals 4.45cm or 1.75″. When you look at buying your web server be sure to check this - it will normally be expressed as a 1U, 2U, 3U or 4U server. The bigger the U number the more your monthly cost will be as your server will be taking up more rackspace.

The other finite resource per rack is the power supply and, therefore, the more power-hungry your server is the more it’s going to cost you. This is one reason why more modern servers are better value in the long run as they are more efficient. For example, Intrahost’s new HP ProLiant G360 G6 servers use 40% less power and are 100% more energy efficient than just the previous generation of G5 ProLiants -  a point worth remembering if you are being offered a “bargain” deal on a three year-old server. Power usage is measured in amps.

Choosing your colocation

When you decide to colocate your web server with Intrahost you have to decide:

• in which data centre do you want it physically locating? Manchester, Barnsley, Leeds, Hull or Sheffield

• what is the U size of your server and its amp usage? Charges are based on whichever is the greater.

• what is the dedicated bandwidth you want? 1Mbps or up to 5Mbps (if you’re not sure you can look at the price and pick the one within your budget)

• installation type: you have a choice of either accompanied installation, this is where you would meet our engineers at the datacentre who would assist you with getting your equipment in, but the configuring of the equipment would be down to you,or  configuring the equipment first, then having it shipped to us for our engineers to install at the data centre; this is usually the quickest and cheapest option.

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