CDFOM flashcards
CDFOM · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- MTTR
- Mean time to repair: the average elapsed time from failure occurrence to full service restoration, including diagnosis, parts, and testing. Used with MTBF to calculate predicted availability.
- MTBF
- Mean time between failures: total operating hours of a population divided by the number of failures in that period. A reliability measure; it excludes repair time.
- Standard change
- A pre-authorised, low-risk change with a documented procedure that has already been approved. It can be implemented without a fresh CAB review each time, but is still logged.
- Emergency change
- A change implemented to restore service or remove imminent risk before normal approval can occur. Requires defined authorisation and a retrospective review after implementation.
- Shift handover record
- A written and verbal briefing at shift change covering open incidents, pending changes, active permits, inhibited alarms, and scheduled vendor activity, signed by both outgoing and incoming leads.
- Predictive maintenance
- Condition-based maintenance triggered by measured trends such as vibration, oil analysis, or thermal rise, so intervention occurs before functional failure rather than on a fixed calendar.
- Comprehensive maintenance contract
- A contract in which the vendor supplies labour, spare parts, and consumables for covered equipment, usually for a fixed fee, transferring parts-cost risk to the vendor.
- Response time versus fix time
- Response time is the interval until the vendor acknowledges and attends; fix time is the interval until service is restored. Contracts must define both separately with distinct remedies.
- Load bank test
- A test applying a controlled resistive or resistive-reactive load to a generator or UPS to verify output, cooling, and fuel performance at rated capacity, independent of IT load.
- Battery impedance trending
- Periodic measurement of battery string impedance or conductance compared against a baseline; a rising trend indicates a degrading cell before capacity testing reveals failure.
- Arc flash boundary
- The distance from energised equipment at which incident energy falls to the threshold requiring arc-rated PPE. It depends on fault current, clearing time, and working distance.
- Lockout/tagout
- An energy isolation procedure: notify, shut down, isolate, apply lock and tag, release stored energy, and verify zero energy before work begins.
- Cross-zoning
- A detection design in which an alarm requires two independent detectors to trigger before suppression release or power isolation, reducing false discharges from a single faulty detector.
- Room integrity test
- A door fan pressurisation test measuring enclosure leakage to confirm the room can retain the design concentration of clean suppression agent for the required hold time.
- Impairment permit
- A formal authorisation to disable or bypass a fire protection system, recording the reason, duration, compensatory measures such as fire watch, and restoration sign-off.
- Relief factor
- A multiplier applied to base headcount to cover planned and unplanned absence, training, and leave. Typically 1.15 to 1.25 for standard operations, higher for 24/7 critical cover.
- Skills matrix
- A table mapping each role or individual against required competencies, showing current proficiency and identified gaps. Used to plan training and verify shift coverage capability.
- Switching authorisation
- A named, documented, revocable permission for a specific individual to operate defined electrical or mechanical systems, granted only after training, assessment, and supervised practice.
- N+1 shift staffing
- Staffing each shift with one more qualified person than the minimum required, so a single absence does not drop the shift below the safe operating minimum.
- Residual risk
- The risk remaining after existing controls and planned treatments are applied. It is compared against the risk appetite to decide whether further action is required.
- Corrective action plan
- A documented response to an audit finding stating root cause, the specific action, the responsible owner, the completion date, and the evidence that will demonstrate closure.
- Separation of duties
- A control assigning approval, execution, and verification of a critical activity to different people, reducing the chance of error or misuse going undetected.
- Document control
- A system ensuring each controlled document has an owner, version, effective date, approval record, review cycle, and that superseded versions are withdrawn from use.
- Risk appetite
- The level of risk an organisation is willing to accept in pursuit of its objectives. Used as the threshold against which residual risk scores are judged.
- Concurrent maintainability
- The ability to perform maintenance on any single component without shutting down the critical load. Requires redundancy at every dependency, including power, cooling, and controls.
- 2N redundancy
- A topology with two complete, independent capacity paths, each able to carry the full load alone. Both paths must be verified end to end to claim the rating.
- RTO
- Recovery time objective: the maximum acceptable duration to restore a service after disruption. It sets the design target for failover, spares, and staff response.
- RPO
- Recovery point objective: the maximum acceptable amount of data loss expressed as time. It determines backup frequency and replication mode.
- Capacity headroom
- The difference between current utilisation and design capacity, expressed as a percentage. Used to trigger procurement and build actions before constraints affect service.
- Single point of failure
- A component whose failure alone causes loss of the critical load. Identified by tracing each utility and control path end to end for shared dependencies.
- PUE
- Power usage effectiveness: total facility energy divided by IT equipment energy over a defined period. A dimensionless ratio; 1.0 is theoretical perfection, higher values indicate overhead.
- Change advisory board
- A group that reviews normal changes for risk, impact, and scheduling conflicts before approval. Emergency changes use a defined expedited route with later retrospective review.