What is Failover? — UK Software Development Guide

4 min readJune 2025ClickMasters Technical TeamReviewed by James Whitmore, CTO
what is failover software

Direct Answer

Failover is the automatic or manual process of switching from a failed or degraded primary system to a secondary (backup) system to maintain service availability. Failover mechanisms include: active-passive (backup takes over when primary fails), active-active (load distributed across multiple systems, all of which can handle full load), and geographic failover (switching between data centres or cloud regions).

Failover in the UK

Failover has specific UK regulatory significance. FCA operational resilience (PS21/3): regulated firms must demonstrate the ability to remain within impact tolerances during disruption — failover mechanisms are the technical implementation of this capability. NHS DSP Toolkit Standard 10 (business continuity): NHS-connected software must have documented failover procedures. ClickMasters designs failover for UK data residency compliance: UK primary (AWS eu-west-2 London) with UK-adequate failover target (AWS eu-west-1 Ireland — Ireland is adequate for UK transfers). Never failover to a non-adequate country without appropriate safeguards (IDTA).

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