The ultimate audit guide to ISO 27001 Annex A 8.14 Redundancy of Information Processing Facilities
Table of contents
- 1. Redundancy Requirements Definition Verified
- 2. Single Points of Failure (SPOF) Analysis Confirmed
- 3. Dual Power Supply and UPS Integrity Validated
- 4. Network Path Diversity Verified
- 5. High Availability (HA) Cluster Functionality Confirmed
- 6. Cloud Availability Zone (AZ) Distribution Validated
- 7. Redundant Component Maintenance Records Present
- 8. Environmental Control Redundancy Confirmed
- 9. Failover Drill and Testing Evidence Verified
- 10. Management Review of Redundancy Metrics Recorded
1. Redundancy Requirements Definition Verified
Verification Criteria: Business requirements for the availability of information systems are formally documented, identifying specific redundancy levels for critical assets.
Required Evidence: Business Impact Analysis (BIA) or Service Level Agreements (SLAs) specifying Uptime requirements.
Pass/Fail Test: If the organisation cannot identify which facilities require redundancy based on a formal risk or impact assessment, mark as Non-Compliant.
2. Single Points of Failure (SPOF) Analysis Confirmed
Verification Criteria: A technical review of the architecture has been conducted to identify and mitigate single points of failure in hardware, software, and utilities.
Required Evidence: Network topology diagrams and infrastructure maps showing redundant paths and failover mechanisms.
Pass/Fail Test: If a single hardware failure (e.g. a lone edge router or power feed) can cause a total system outage for a critical service, mark as Non-Compliant.
3. Dual Power Supply and UPS Integrity Validated
Verification Criteria: Critical equipment is supported by redundant power feeds, including Uninterruptible Power Supplies (UPS) and secondary generators.
Required Evidence: Physical inspection or data centre maintenance logs confirming dual power distribution units (PDUs) and UPS load-test certificates.
Pass/Fail Test: If critical servers are connected to a single PDU or if the UPS fails a simulated load-transfer test, mark as Non-Compliant.
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4. Network Path Diversity Verified
Verification Criteria: Redundant telecommunications and network paths are utilised, entering the building at geographically diverse points to prevent accidental severance.
Required Evidence: ISP contracts and site drawings showing diverse entry points (e.g. North and South building entries).
Pass/Fail Test: If redundant network lines share the same physical conduit or entry point into the facility, mark as Non-Compliant.
5. High Availability (HA) Cluster Functionality Confirmed
Verification Criteria: Server and database environments are configured in High Availability clusters (Active/Active or Active/Passive) with automated failover triggers.
Required Evidence: Cluster heart-beat logs and failover configuration settings in the hypervisor or cloud console.
Pass/Fail Test: If failover between redundant nodes requires manual intervention and exceeds the RTO specified in the BIA, mark as Non-Compliant.
6. Cloud Availability Zone (AZ) Distribution Validated
Verification Criteria: For cloud-hosted services, instances and data are distributed across multiple Availability Zones to protect against regional data centre failures.
Required Evidence: Cloud console configuration (e.g. AWS/Azure/GCP) showing resource deployment across at least two distinct zones.
Pass/Fail Test: If all cloud production resources reside in a single Availability Zone without a cross-region backup or failover, mark as Non-Compliant.
7. Redundant Component Maintenance Records Present
Verification Criteria: Secondary and redundant components undergo regular maintenance and testing to ensure they remain operational when needed.
Required Evidence: Preventive Maintenance (PM) logs for backup generators, secondary cooling units, and failover switches.
Pass/Fail Test: If the primary system is maintained but the redundant system has no service history for the last 12 months, mark as Non-Compliant.
8. Environmental Control Redundancy Confirmed
Verification Criteria: Cooling and HVAC systems are designed with N+1 or 2N redundancy to maintain temperature even during a unit failure.
Required Evidence: Physical sighting of redundant HVAC units and historic temperature logs showing stability during maintenance windows.
Pass/Fail Test: If a single cooling unit failure results in a server room temperature exceeding manufacturer thresholds, mark as Non-Compliant.
9. Failover Drill and Testing Evidence Verified
Verification Criteria: Regular testing of the failover mechanisms is conducted to ensure that the redundant systems activate correctly under load.
Required Evidence: Post-test reports from “Scenario-based Failover Drills” or recent disaster recovery (DR) test results.
Pass/Fail Test: If the organisation claims redundancy but cannot provide a report of a successful failover test within the current audit year, mark as Non-Compliant.
10. Management Review of Redundancy Metrics Recorded
Verification Criteria: Management reviews the adequacy of redundancy measures against changing business needs and incident history.
Required Evidence: Management Review Meeting (MRM) minutes showing discussions on availability trends and infrastructure investments.
Pass/Fail Test: If recurring availability incidents occur but there is no evidence of management reviewing redundancy gaps, mark as Non-Compliant.
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