Choosing the most suitable IT rack

What will the IT rack be used for?

Both server and network technology can be housed in an IT rack and the use of the rack determines its size and dimensions.

In a network rack, individual components are laterally cabled in a comprehensive way, which explains the width of 800mm while the depth may be up to 1,000mm.

By contrast, 600mm width is sufficient for a 'pure' server rack because the power cables are at the rear and do not require any space at the sides. The rack is typically 1,000 to 1,200mm deep.

In the case of mixed configuration, with server and network technology within a single rack, the width must be 800mm and the depth 1,000 to 1,200mm. This means that network distributors, patch panels and PDUs for power supply can be comfortably installed, as can larger numbers of cables.

The suitable respective heights are determined from the height Units (U) required. A rack with 42U is around 2m high, which is the most common height these days.

Where is the rack located, and how should it be protected?

IT racks are installed not only in data centres but also in offices, production buildings etc.

The location of the rack defines the protection requirements and safety class, which is expressed in the IP (International Protection) standard. If the IT rack is in an office environment, access protection as per IP 20 (with a lockable door) is sufficient. A rack in a production building, however, needs to be lockable. With IP 55 protection, it also needs to be safeguarded against dust and jets of water.

IP 20 protection is sufficient in a closed data centre. Here, it isn’t necessary for the individual racks to be lockable, as only authorised persons have access. Access to individual racks is controlled through an electronic lock, a card reader, or a transponder. Personalised access control via a transponder card or a uniquely assigned numeric code identifies who had access to the server rack, and when. Taking this a step further, a dual control, counter-checking system ('four-eye-principle') is also feasible, where two people have to provide identification at the same time.

How is heat dissipation performed?

The technology inside the rack produces waste heat, which has to be dissipated to protect the sensitive electronic components and increase their service life.

If a single rack is to be cooled, a climate control unit must be installed. This blows the cooled air directly at and in front of the server level. The rack must have a closed (glass) door, so that the air cannot escape into the room.

Meanwhile, perforated doors with a cooling system are required for bayed racks and rooms in order to extract the cool air from the room and/or cold aisle.

How does the power supply and distribution work?

A UPS unit will filter out the voltage fluctuations that are harmful to IT components. In addition, the power supply can take over temporarily during a power failure thanks to its battery mode.

PDUs then distribute the power within the rack.

How are access to facility management and integration into building management systems achieved?

Facilities management typically has to manage the monitoring of external parameters. This includes the temperature of the cooling water supplied from outside to the air/water heat exchangers for cooling the IT racks.

If the climate control unit for cooling the racks is an active version, monitoring of the humidity will be necessary.

Surveillance at the IT rack, e.g. the monitoring of temperature, smoke, power consumption and vandalism, must also be integrated into the building management system. It is vital that the monitoring solution supports standard protocols such as SNMP (Simple Network Management Protocol) for the connection to DCIM (Data Centre Infrastructure Management) software, or OPC UA (object linking and embedding for process control unified architecture for linking to building control).

Practical tip: use the manufacturers’ selection guides

Rittal offers a selector that makes it easier to choose a suitable IT rack. This helps the user to decide from more than 100 options and provides clear explanations.