CDCP flashcards
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32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Concurrently maintainable
- A Tier III characteristic: any piece of equipment can be removed from service for planned maintenance without affecting the IT load, because an alternative distribution path exists.
- Fault tolerant
- A Tier IV characteristic: the facility has multiple independent, simultaneously active capacity and distribution paths, so a single failure of any component does not affect the IT load.
- 2N redundancy
- Two complete, independent capacity systems each able to carry the full load. A failure or maintenance in one system leaves the other serving the entire IT load.
- N+1 redundancy
- One additional module beyond the number needed to carry the load. If N modules are required, N+1 provides one spare that covers a single module failure or maintenance event.
- ANSI/TIA-942
- A telecommunications infrastructure standard for data centres covering site, architectural, electrical, mechanical and cabling requirements, with rated levels from I to IV.
- EN 50600 series
- European standard series for data centre facilities and infrastructures, defining availability classes, physical security, energy efficiency and related design and operation requirements.
- Basis of design
- The design document stating IT load, rack density, redundancy level, growth allowance, environmental targets and applicable standards that all later design decisions must satisfy.
- Hot and cold aisle layout
- Rack arrangement where equipment intakes face a common cold aisle and exhausts face a common hot aisle, preventing supply air from mixing with return air before cooling.
- Three-phase power formula
- Real power in watts equals √3 multiplied by line-to-line voltage, line current and power factor. Apparent power in VA omits the power factor term.
- Power factor conversion
- Apparent power in kVA equals real power in kW divided by power factor. A 900 kW load at 0.9 power factor requires 1,000 kVA of capacity.
- PUE definition
- Power usage effectiveness equals total facility energy divided by IT equipment energy. A value of 1.0 is ideal; 1.5 means half a unit of overhead per unit of IT energy.
- UPS battery autonomy
- The runtime a battery string provides at a given load. Runtime falls roughly with load increase, and faster than linearly at high discharge rates.
- Static transfer switch
- A device that switches a load between two independent power sources in milliseconds, used to feed rack PDUs from A and B feeds without a break.
- Generator block loading
- The stepwise application of load to a generator set. Large single steps can exceed the alternator's capability and cause voltage and frequency excursions.
- TN-S earthing system
- An earthing arrangement where protective earth and neutral are separate conductors throughout the installation, reducing stray currents and noise on the earthing system.
- A and B rack feeds
- Two independent power supplies to dual-corded IT equipment, each sized to carry the full rack load, so loss of one feed leaves equipment running.
- Sensible heat airflow formula
- Cooling power in kW equals airflow in m3/s times air density 1.2 kg/m3 times specific heat 1.005 kJ/kgK times the supply-to-return temperature difference in kelvin.
- Airflow per kW rule
- Roughly 1.7 to 2.0 cubic metres per minute of supply air is needed per kW of IT load at a 10 to 12 kelvin temperature difference.
- ASHRAE recommended envelope
- The intake air range recommended for reliable IT operation, broadly 18 to 27 degrees Celsius with humidity limits that prevent electrostatic discharge and condensation.
- Hot aisle containment
- Physical enclosure of the hot aisle so exhaust air returns directly to cooling units, preventing hot air from recirculating into equipment intakes.
- Cold aisle containment
- Enclosure of the cold aisle with doors and roof panels so supply air reaches equipment intakes without escaping or mixing with hot exhaust air.
- Refrigeration ton
- A cooling capacity unit equal to 3.517 kW of heat removal. Chiller plant efficiency is often expressed as kW per ton of cooling delivered.
- Coefficient of performance
- Cooling output in kW divided by electrical input in kW. A COP of 4 means four units of cooling are produced per unit of electrical energy consumed.
- Free cooling hours
- The annual hours when outdoor conditions allow cooling without mechanical refrigeration, determined by local climate and the chosen supply air or water temperature.
- Method of procedure
- A controlled document giving step-by-step instructions for a specific task, with prerequisites, approvals, verification steps and a rollback plan if the task fails.
- Standard operating procedure
- A documented routine process describing how recurring operational tasks are performed consistently, including roles, steps and acceptance criteria.
- Emergency operating procedure
- A pre-written response plan for defined failures such as power loss, cooling failure or fire, specifying immediate actions, escalation and recovery steps.
- Incident versus problem
- An incident is an unplanned interruption or service degradation. A problem is the underlying cause, addressed through root-cause analysis to prevent recurrence.
- Integrated systems test
- A commissioning test that runs the whole facility together, including full-load operation and simulated failures, to prove systems interact correctly before handover.
- Mean time to repair
- The average time needed to restore a failed component or system to service, a key input to availability calculations and spares strategy.
- Mean time between failures
- The average operating time between failures of a repairable system. Combined with repair time, it determines the availability of that system.
- Capacity threshold alert
- A configured warning level on power, cooling, space or network utilisation that triggers action before a hard limit is reached, preserving headroom for growth.