19-inch racks: Everything you need to know about server cabinets, accessories and cooling

A well-organised IT infrastructure is not just about servers, switches and network technology. Where they are housed also plays an important role.

Whether in a small office, a server room or a data centre: 19-inch racks and server cabinets provide the physical framework for a structured IT environment. But not all racks are the same – and what may look like a simple cabinet at first glance must meet a wide range of requirements in day-to-day operation.

What is a rack and what is it used for?

A rack is a frame or cabinet in which IT equipment such as servers, switches, routers and UPS units can be housed in a space-saving and organised manner. It ensures that the hardware is arranged in a structured way and makes installation, cabling and maintenance easier. Racks are primarily used in corporate networks, server rooms and data centres.

19-inch racks, which have a standardised installation width, are particularly common. The 19 inches (48.26 cm) refer to the width of the front of the equipment or the mounting level, and not to the external width of the cabinet. The available installation height is specified in height units (HU), with one HU equalling exactly 44.45 mm. Thanks to this standardisation, different IT components can be combined within a single rack, provided that the installation depth, mounting method and load capacity are also compatible.

Advantages of racks

• Space-saving organisation: Servers, switches, routers and other IT components can be housed centrally and in a clearly organised manner.
• Easy maintenance: The structured layout facilitates access to devices, cables and connections, as well as the replacement of individual components.
• Flexible expandability: Thanks to standardised installation dimensions, compatible devices can be added or replaced as required.
• Integrated power supply: Rack-mountable UPS systems can temporarily continue to supply power to connected devices in the event of a power cut.
• Targeted cooling: Depending on their design, racks allow for appropriate airflow so that warm air can be extracted and the hardware adequately cooled.

What types of racks are there?

Not every rack is suitable for every IT environment. Depending on the existing hardware, available space and security and maintenance requirements, different designs may be appropriate. The most common types of racks include server cabinets, network cabinets, open racks and compact wall-mounted enclosures.

Note: The categories overlap to some extent. ‘Server’ and ‘network’ cabinets primarily describe the intended use, whilst ‘open’, ‘enclosed’ and ‘wall-mounted’ refer to the design.

What is important when choosing a rack type?

The decisive factor is not simply the name of the rack, but whether it meets the technical requirements of the existing IT hardware. Whilst a compact wall-mounted enclosure is often sufficient for smaller network installations, large-scale server installations usually require larger floor-standing racks with the appropriate installation depth and load-bearing capacity.

The installation location also plays a role: open racks facilitate access to the equipment but offer little protection against unauthorised access. Enclosed server cabinets, on the other hand, are often the better choice when hardware needs to be protected and airflow needs to be carefully managed.

What is the right rack size?

The right rack size depends on which and how many devices are to be housed in it. A rack that is too small makes subsequent expansion and cabling more difficult, whilst an oversized server rack can take up unnecessary floor space. The key factors for making the right choice are, above all, the height units (HU), the rack width, the installation depth and the load capacity.

1. Rack height: How many U are required?

The height of a 19-inch rack is specified in units of height (U). The more units of height a rack has, the more space is available for mounting hardware.

To determine the required rack height, add together the height units of all the planned devices. In addition, sufficient space should be allowed for accessories, any necessary clearances and future expansions.

Calculation example: A company wishes to house two switches (each 1U), a server (2U), a UPS (2U) and two patch panels (each 1U). Together, this amounts to a space requirement of 8U. If a further 4U is set aside as reserve, a rack with a minimum capacity of 12U would be a possible choice, provided that the load capacity, installation depth and other requirements are met.

2. Rack width: 600 or 800 mm?

In a standard 19-inch rack, the width of the mounting level is standardised. The 19 inches correspond to 48.26 cm and refer to the standardised installation dimension, not the external width of the cabinet.

For free-standing server cabinets, two external widths are particularly common:

• 600 mm: A space-saving solution for installations with manageable cabling requirements.
• 800 mm: Offers more space at the sides for cable routing and is particularly suitable where there are many network and power cables.

3. Rack depth: How much installation space is required?

The depth of a rack must be tailored to the longest or deepest pieces of equipment. Whilst compact network devices often take up little space, rack-mounted servers and larger UPS systems often require significantly more installation depth.

Typical external depths for server cabinets are 600, 800, 1,000 and 1,200 mm. Compact wall-mounted enclosures are also frequently available with depths of 450 or 600 mm.

Important: The specified cabinet depth usually corresponds to the external dimension and not necessarily to the usable installation depth. Therefore, before purchasing, you should check the dimensions of the equipment, the adjustment range of the mounting rails and the space available for connections or cables.

4. Rack load capacity: How heavy can the hardware be?

In addition to the dimensions, the weight of the installed equipment plays an important role. Servers, storage systems and UPS units in particular can have a high total weight.

The rack’s permissible load capacity must therefore be sufficient to safely support all equipment, including accessories. A distinction should be made between the static load capacity when the rack is in place and, where applicable, the specified dynamic load capacity during transport or movement. Heavy components are generally mounted as low down as possible to keep the centre of gravity low.

Which 19-inch racks are suitable for which applications?

Whilst compact design and easy assembly are often the main priorities for smaller installations, load capacity, cable management and expansion options are the key factors for large-scale server installations. Manufacturers such as APC, Eaton and Vertiv offer a range of rack series designed to meet these specific requirements.

APC Racks: Flexible solutions for servers and networks

APC’s 19-inch racks are suitable for a variety of IT environments. The Easy-Rack series, in particular, offers a practical solution for businesses wishing to house servers, switches or other network devices in a centralised location. Adjustable mounting rails, cable grommets and the option to integrate rack accessories make it easy to adapt the racks to existing hardware.

For decentralised IT sites and edge computing applications, APC also offers the Easy Micro Data Centre series. Depending on the model, these pre-configured solutions combine power supply, cooling and monitoring components within a single rack enclosure.

You can find further models under APC Racks and Cabinets.

Eaton Racks: For compact IT installations

Eaton’s racks offer a range of solutions for housing network equipment, servers and UPS systems. The SmartRack series, in particular, comprises various sizes, making it suitable for both small IT installations and more extensive server environments.

For locations with limited space, Eaton also offers the SRW range. This comprises compact, predominantly wall-mounted rack enclosures, which are suitable, for example, for offices, retail spaces or smaller network distribution centres.

You can find further details under Eaton Racks.

Vertiv Racks: For demanding server environments

Vertiv’s 19-inch racks are designed specifically for businesses with extensive server, network and storage installations. The Vertiv VR series combines high load-bearing capacities with a range of cabinet dimensions and options for structured cable management. Depending on the model, the racks can also be integrated into data centre designs featuring separate supply and exhaust air systems.

You can find more models under Vertiv Racks.

What rack accessories are required?

However, additional rack accessories are often required to ensure that servers, switches and other devices can be securely mounted, powered and neatly cabled. Which components form part of the basic setup depends on the hardware installed and the specific application.

Shelves and mounting rails

• Not every IT device can be mounted directly in a 19-inch rack. Rack shelves provide a stable surface for devices that do not have their own rack mounting. Mounting rails and suitable rack-mount kits, on the other hand, enable compatible servers and other hardware to be securely mounted.

Cable management

• Where many devices are installed, a large number of power and network cables can quickly accumulate. Cable managers and cable guides help to route these cables neatly through the server cabinet. This makes troubleshooting easier and improves accessibility during maintenance work.

Power strips and rack PDUs

• Rack PDUs (Power Distribution Units) are frequently used to supply power to multiple devices. These distribute electrical power to the connected components and are available in various designs.

Blind plates and fan units

• Even unused areas within a server cabinet can affect airflow. Blind plates seal off empty height units and help to reduce the unwanted mixing of warm and cold air. Additional fan units can support air circulation if the existing ventilation is insufficient.

UPS systems for power supply protection

• An uninterruptible power supply (UPS) is not necessarily part of the standard equipment for every rack, but can be an important addition for business-critical IT systems. In the event of a power cut, it continues to supply power to connected devices for a limited period of time.

Suitable rack accessories at IT-Planet

Why is proper rack cooling important?

Servers, switches, UPS systems and other IT equipment generate heat during operation. If this heat is not adequately dissipated, the temperature inside the rack can rise, impairing the hardware’s performance. A well-designed rack cooling system helps to prevent overheating, temperature-related performance losses and unplanned downtime.

However, it is not just a matter of adding extra fans. It is crucial that the devices can draw in sufficient cool air and that their warm exhaust air does not recirculate back to the intake side. The room temperature, the layout of the hardware and the design of the rack also influence cooling.

Passive and active rack cooling

• Passive rack cooling: Utilises existing ventilation openings, perforated doors and appropriate airflow management without the use of additional rack fans. It may be sufficient for installations with low heat generation, provided that the equipment itself is adequately ventilated and the ambient temperature is suitable.
• Active rack cooling: Uses additional fans or specialised cooling systems to specifically support air circulation or heat dissipation. It may be necessary in cases of higher heat loads or unfavourable installation conditions.

How can air circulation in a server rack be improved?

Many rack-mounted servers operate on the front-to-back principle: they draw in cooler air at the front and expel heated air at the rear. For this principle to work, air pathways must remain unobstructed and the intake and exhaust air should be kept as separate as possible.

The following measures can help:

• Perforated rack doors: Allow air to circulate and aid the cooling of appropriately configured servers.
• Blanking plates: Seal off unused height units and reduce the unwanted backflow of warm air towards the front of the rack.
• Brush strips: Cover cable entry points and can reduce uncontrolled airflow through openings.
• Rack fans: When positioned correctly, they assist with airflow within or out of the server cabinet.
• Temperature monitoring: Helps to detect critical temperature trends at an early stage.

Which products support rack cooling?

What should businesses look out for when buying a rack?

Whether it’s a compact network rack or a large server cabinet, it is crucial that the size, load capacity, accessories and cooling are tailored to the hardware being used. By also taking into account the installation location, security and potential for future expansion, you can lay a suitable foundation for a well-organised IT infrastructure.

Are you looking to buy a 19-inch rack or a server cabinet? Discover a selection of racks and matching accessories from APC, Eaton and Vertiv at IT-Planet to suit a range of requirements – from small business networks to data centres. Simply enquire via our enquiry form.