Glass door racks are a type of rack that have solid glass front doors and rear door heat exchangers (RDHx).
RDHx are devices that use facility coolant to absorb heat from the exhaust air of the IT equipment and return cool air to the room. RDHx can be either passive or active, depending on the fan configuration. In general, IT hardware within the rack is air-cooled and the door heat exchanger uses facility coolant to absorb heat from exhaust air to return air to the facility at or near inlet air temperature to the rack. This rear door heat exchanger can either be a passive or active solution. When dealing with glass door racks, cool air is injected into the rack from the rear door in a downflow direction. This means that the cool air flows from the top to the bottom of the rack, following the natural convection of the hot air rising. This way, the cool air can reach all the IT equipment in the rack and prevent hot spots or overheating.
References: [SOLVED] Rack - Solid or Mesh front door? - Data Center
IT](https://community.spiceworks.com/topic/510677-rack-solid-or-mesh-front-door), ChilledDoor, Rear Door Heat Exchanger | Data Center Cooling, ACS Door Heat Exchanger Requirements for Open Rack.

Glass door racks are a type of rack that have solid glass front doors and rear door heat exchangers (RDHx).
RDHx are devices that use facility coolant to absorb heat from the exhaust air of the IT equipment and return cool air to the room. RDHx can be either passive or active, depending on the fan configuration. In general, IT hardware within the rack is air-cooled and the door heat exchanger uses facility coolant to absorb heat from exhaust air to return air to the facility at or near inlet air temperature to the rack. This rear door heat exchanger can either be a passive or active solution. When dealing with glass door racks, cool air is injected into the rack from the rear door in a downflow direction. This means that the cool air flows from the top to the bottom of the rack, following the natural convection of the hot air rising. This way, the cool air can reach all the IT equipment in the rack and prevent hot spots or overheating.
References: [SOLVED] Rack - Solid or Mesh front door? - Data Center IT](https://community.spiceworks.
com/topic/510677-rack-solid-or-mesh-front-door), ChilledDoor, Rear Door Heat Exchanger | Data Center Cooling, ACS Door Heat Exchanger Requirements for Open Rack.

Hot- or cold-aisle containment is a strategy to improve the cooling efficiency and reduce the energy consumption of data centers by isolating the hot exhaust air from the cold supply air. However, implementing this strategy in an existing computer room may create potential issues with the existing fire suppression system (s), such as:
*The containment barriers may interfere with the distribution and activation of the fire suppression agents, such as water, gas, or aerosol, and reduce their effectiveness in extinguishing a fire.
*The containment barriers may create pockets of high temperature and pressure that could damage the equipment or the containment structure itself in the event of a fire.
*The containment barriers may obstruct the access and visibility of the fire detection and alarm devices, such as smoke detectors, heat sensors, or manual call points, and delay the response time of the fire suppression system(s).
*The containment barriers may violate the local fire codes and regulations that specify the minimum clearance and ventilation requirements for the data center.
Therefore, when implementing hot- or cold-aisle containment in an existing computer room, it is important to consider the impact on the existing fire suppression system(s) and take appropriate measures to ensure the safety and compliance of the data center, such as:
*Consulting with the fire authorities and the fire suppression system vendor to assess the compatibility and suitability of the containment solution with the existing fire suppression system(s).
*Modifying or upgrading the existing fire suppression system(s) to accommodate the containment solution, such as relocating or adding fire suppression devices, adjusting the discharge rate and pressure, or installing a secondary fire suppression system within the contained area.
*Installing fire-rated containment barriers that can withstand high temperatures and resist the spread of fire and smoke, and that have self-closing or automatic release mechanisms in case of a fire.
*Installing fire detection and alarm devices within the contained area and ensuring their proper integration and communication with the existing fire suppression system(s).
*Conducting regular testing and maintenance of the fire suppression system(s) and the containment solution to ensure their functionality and reliability.
References: EPI Data Centre Framework, Module 4: Fire Protection, page 10-11. EPI Data Centre Professional (CDCP) Reference Materials, page 66-67. 1, 2, 3.

According to the EPI Data Centre Training Framework, EMF is a form of electromagnetic interference (EMI) that can disrupt or damage the normal operation of electronic devices, such as servers, network cables, and IT equipment1. High levels of EMF can be generated by power equipment, cell phones, microwaves, TV and radio signals, etc., and can cause data corruption, data loss, system malfunction, and crashes23. Therefore, EMF can cause data centre failures and affect the availability, performance, and security of the data centre. To prevent or mitigate EMF, data centres should follow the best practices for data centre design, layout, cabling, grounding, shielding, and testing14.
References: 1: EPI Data Centre Training Framework, Module 5: Power, Section 5.4.1: Electromagnetic Interference, Page 5-34 2: EMI in the Data Center: To Shield Or Not ToShield2 3: Electromagnetic Interference in Data Centers: Risks Involved and Its Impact on Information Security4 4: Data Center Electromagnetic Interference and Tier Standards1

A fire extinguisher in the data centre that is classed as ABC is not suitable, because it contains dry chemical powder that can damage the ICT equipment and the data. ABC fire extinguishers are designed to fight Class A, B, and C fires, which are fueled by combustible materials, flammable liquids or gases, and electrical equipment, respectively. However, the dry chemical powder can leave a corrosive residue on the ICT equipment, which can cause short circuits, data loss, or malfunction. Moreover, the dry chemical powder can be difficult to clean, especially from the small spaces and crevices of the ICT equipment. Therefore, ABC fire extinguishers are not recommended for data centres, and should be replaced with more suitable fire extinguishers, such as clean agent fire extinguishers, which use gas or liquid that does not leave any residue or harm the ICT equipment.
References:
1: CDCP Preparation Guide, page 24, section 2.4.3 2: Data Center Fire Suppression: Overview & Protection Guide3, page 1, section 1 4: Fire Extinguisher Classes and Suitability5, page 1, section 1 6: SAFETY DATA SHEET Commercial ABC Dry Chemical (Fire Extinguishing Agent ...7, page 1,