Rack space refers to the amount of physical space your server or servers take up in a rack in a co-location facility. Typical full racks are 42 units (see below) and run from floor to ceiling. The colocation facility provides the access to the network and you basically rent space to house your servers in either a cabinet or an open rack. You typically buy a server that can be mounted on racks in the cabinet, therefore the space you rent is referred to as "rack space".

Typically rack mount servers are referred to in size as 1 U, 2 U, etc. This refers to how many slots machine occupies in the rack or cabinet. 1 U in our co-location facility is about 1.75". If you have a rack mount server the vendor you purchased it from can tell you what size it is. Otherwise you can calculate the size based on 1 U roughly being equal to 1.75". If you have a tower server, you can measure the width of the server including the base because these type of servers can be put in horizontally on their side, though we recommend purchasing a rack-mount server if you are purchasing a new server.

Rack space is typically available from colocation facilities on a per 1U, per cabinet or per half-cabinet basis. If you are getting a half-cabinet you have to consider who will be sharing the other half of the cabinet and will potentially have access to your servers. Also the cost of a half or full cabinet may be out of the price range of some companies. Server colocation also requires budgeting for staff to maintain servers on a 24 x 7 basis and potentially travel to the data center in case of emergency or pay on site staff expensive fees to reboot servers. In order to minimize your need to be on-site, you should work with your colocation provider to develop a management plan. Most co-location providers offer what is called "managed co-location" in which the bulk of the routine management is handled by a member of the provider's staff.

A managed hosting company will rent you space and perform some management of your services and software. This rack space comes with outsourced services so you don't have to employ 24 x 7 staff to monitor and maintain networks, hardware, security, backups and software. They will typically manage some network, hardware, operating and possibly database administration functions. However you will still be responsible in most cases for any problems with your data or your application. You will need to employ in house or contract developers and database support staff to resolve issues with application code caused by problems with your data, errors or hackers. You may end up in a situation where you think the problem is due to the network or server and your managed hosting company things the problem is with the application.