ISO/IEC 27001:2022 Annex A · Control 8.14

Redundancy of Information Processing Facilities: A Practical Implementation Guide

Design and test redundancy so critical services tolerate component and location failures.

This control concerns implementing sufficient redundancy in information-processing facilities to meet availability requirements.

Practical interpretation: Duplicated components provide resilience only when failure domains, capacity, configuration, data consistency and failover are understood and tested.

What should the control achieve?

Redundancy requirements follow availability objectives.
Components are separated across realistic failure domains.
Failover capacity and data consistency are sufficient.
Tests demonstrate service continuity.

Step-by-step implementation

Define availability needs

Use business impact, RTO, tolerated interruption and transaction integrity.

Map failure domains

Consider power, rack, network, zone, region, provider and administration.

Design redundancy

Choose active-active, active-passive, clustering, replication or alternate providers.

Manage consistency

Define replication lag, split-brain and recovery behavior.

Monitor readiness

Track health, capacity, synchronization and standby configuration.

Test failover and failback

Exercise realistic failures and restoration.

What this could look like in practice

An online service runs across two availability zones with independent power and network paths. Automated failover is tested quarterly, and capacity planning confirms one zone can carry essential load.

Activity	Practical implementation	Evidence
Component failure	Cluster continues service after node loss.	Test log
Zone failure	Traffic moves to alternate zone.	Exercise report
Replication	Lag and integrity thresholds are monitored.	Dashboard
Failback	Controlled return avoids data conflict.	Change record

Implementation evidence

Availability requirements
Failure-domain map
Architecture design
Capacity analysis
Replication monitoring
Failover tests
Failback procedures
Test actions

Useful metrics

Failover tests passed
Redundant capacity available
Replication threshold breaches
Single points of failure

Common mistakes

Placing redundant systems on one power source.
Assuming cloud zones are independent without design review.
Testing failover but not failback.
Insufficient standby capacity.
Replicating corruption instantly.

Questions an auditor may ask

Which failures must the service tolerate?
How are failure domains separated?
Show a failover test.
How is data consistency protected?

Implementation test: Disable a representative component or zone and verify automatic or manual failover, capacity, data integrity and controlled return.

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This independent educational guide paraphrases the practical intent of the control and does not replace the official ISO standards, professional advice or an organization-specific risk assessment. It is not affiliated with or endorsed by ISO.

ISO 27001 Annex A 8.14: Redundancy of Information Processing Facilities – Practical Implementation Guide