Colocation Series #2 – Rack space

Colocation Series #2 – Rack space

There are a variety of colocation options available to a business when considering hosting in a datacentre. The majority of colocation services are provided using server racks or cabinets (these terms are used interchangeably). The most common rack specification is 19”, 42U rack, with a width of 600mm and a depth of 1100mm.

The rack unit, “RU” (or “U” as it is more commonly known) describes the size of the equipment typically installed in a rack. 19” refers to the width of the vertical mounting frame where equipment is installed. A typical 42U rack is approximately 6ft in height.

42U is perhaps the most common rack size but a wide range of other form factors are available including 21U, 47U and 48U. In addition to height, larger racks with a greater width (e.g. 750mm) and depth (1200mm) are available which provide more space for cabling and similar accessories.

Server racks are also designed to certain standards that ensure interoperability between equipment vendors. In the majority of cases, anything deemed “rack mountable” normally assumes it will be mounted in a 19” rack.

Many racks feature lockable doors, fitted with key, combination, biometric or remote-locking systems. To aid cooling, rack doors in a datacentre environment are typically meshed steel to allow cool air to access the server equipment.

You can learn more about the actual rack dimensions on the following link.

Colocation Service Options

From a datacentre service perspective, the types of colocation service available typically relate to the amount of space, power and network connectivity the customer requires. As a general rule, the most popular forms of colocation service (or configurations) are as follows:

  • Individual units (‘U’) of rack space
    When there is a requirement to house individual servers, SANs, firewalls or network devices; then individual rack units tend to be used. When a colocation requirement grows beyond 5U or features multiple devices then it is generally more cost-effective to opt for a quarter rack. In an individual “U” environment there will be multiple customers in a rack and access to the equipment is therefore tightly controlled by the service-provider.
  • Quarter-Rack / Half Rack
    When there is a requirement to house multiple servers or devices in the datacentre, but the quantity of devices doesn’t warrant a full rack, a customer can opt for a quarter-rack (10U) or a half-rack (21U) of space. Much like the previous example, access to a shared rack is typically managed and controlled by the service-provider. Segregated and lockable quarter and half rack configurations are also common service options, this is where the rack has two or four lockable doors at the front of the rack and separate cabling conduits.
  • Full rack (or multiple)
    For customers who have a large piece of equipment, have several devices to colocate or where a customer wants the highest levels of segregation and privacy, then a full rack is typically the most popular option. The customer would be granted full access to the rack and is able to customise the characteristics of the rack to suit their needs. This customisation could include the cabling configuration, the power distribution units (PDU) and changes to the rails, the installation of rack-shelves and similar accessories.  In many cases, a customer may opt for several adjacent racks.
  • Private Pods, Suites or Rooms
    When multiple racks or the highest levels of privacy and segregation are required, a customer can opt for a private pod, suite or room. A pod describes a discreet collection of racks in an enclosed configuration. Wi-Manx use a cold aisle containment system (discussed later in cooling) which means the racks are laid out in opposing rows of racks, typically 8 a side (16 in total). A pod enables a client to opt for a number of racks in a private setup. A suite/room is where the racks are located in a completely private room or caged area for the highest level of security.

Wi-Manx delivers a full range of datacentre, network and hosting solutions to customers all over the world, including all of those discussed within this article. We can provide hosting services from both our Isle of Man datacentre and our London and Manchester facilities.

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