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To help distinguish a cabinet from a rack, consider the former as enclosing the latter by way of front and rear doors and side panels. Enclosed cabinets are perceived to offer the best, and simplest, approach to implementing various air segregation strategies: Cold Aisle Containment, Hot Aisle Containment and Cabinet Level Containment. Enclosed cabinets facilitate higher levels of physical security, supporting various types of locking systems to enhance protection from unauthorized entry.

The difference between cabinets and racks

Whilst the distinction is subtle, it can be explained thus.

For the main factors in considering open frame racks and enclosed cabinets, see this article.
 

Cabinet standards

  • Cable management: suitable for larger bundles of cables:

    Cable clip large
     

  • For a few cables a small retainer, together with Velcro, is more suitable:

    Cable clip small
     

  • Inner grooves, that face the racked equipment, allow these cable management solutions to be mounted to the inside of the rack struts, keeping the door apertures free of cabling obstruction and reduce the interruption to airflow.
     

Cabinet security

  • All cabinets are lockable.
  • An intelligent key access management system, utilising an intelligent fob/key cabinet combination, provides control, access and accountability on who may gain direct access to secure keys.
  • Unless work is being undertaken within (a) cabinet(s), all cabinets must remain locked.
     

Cabinet loading

  • Cabinet loading must not exceed the weight rated capacity for the cabinet or the location's solid floor. Cabinet capacity is 1.5 tonnes.
  • Cabinet heat load must not exceed the cooling capacity of the location.
  • Large servers and equipment should be installed at the bottom of the rack.
     

Cabinet air flow

  • WCDC DH3 utilises hot-aisle containment.
  • When racking equipment, it is essential that devices exhaust hot air into the contained aisle.
  • This is most acute for switch devices, where the desire is to orientate the device such that running network cables from the front* to the back** of the cabinet is avoided.

Drawing on Cisco's own documentation:

"The front to back airflow switch comes with matching burgundy color [sic] fan and power supply handle to indicate warm side.

front to back airflow

Similarly, back-to-front airflow switch fan and power supply handles are color-coded in blue to indicate cool side."

bacjk to front airflow

Assumptions

*front – the front of the cabinet is in the cold aisle. When racking servers, the power button and disk drives will, invariably, be accessible from this side.

**back – the back of the cabinet is in the hot-aisle. When racking servers, the power supplies and network ports will, invariably, be accessible from this side.

Airflow sleeves

Cabinet integrity is further enhanced by utilising airflow sleeves in conjunction with switches. These help funnel exhaust air out of the cabinet. Without these, exhaust air circulates within the cabinet, reducing airflow efficiency and, because the heated air isn't vented, the temperature within the cabinet increases.

Cisco Airflow Sleeve s

Cable management arms

The use of server cable management arms (see photo below) is prohibited.

If found to have been installed, clients can expect to be asked to remove them.

cable mgmt arm

The rationale

  • The bars are placed, counter-intuitively, behind fans.
  • This adversely affects the venting of heated air into the hot aisle.
  • Heat retained inside the cabinet creates a hot-spot within the room.
  • Prevents the hall from operating higher temperatures in the cold aisle.
  • Cooling the air intake temperature increases energy consumption.
  • This reduces the efficiency of the facility.
  • This negates the benefits that the facility was intended to provide.
     

Grounding

  • All cabinets and cable delivery pathways must be grounded in compliance with the BS7671 17th Edition wiring regulations.
     

Cabinet resiliency

  • In-rack UPSs are not required... Data Hall 3 has UPS protection.

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