Disaster recovery is the process of planning for and recovering from catastrophic failures that make systems unavailable. Natural disasters, data centre outages, cyberattacks, and human error can cause complete system unavailability. Organisations require disaster recovery plans ensuring critical systems can be restored quickly, minimising business impact and customer disruption.
Recovery Objectives
Defining recovery requirements:
Recovery Time Objective (RTO) - Maximum acceptable downtime. If RTO is 4 hours, systems must restore within 4 hours.
Recovery Point Objective (RPO) - Maximum acceptable data loss. If RPO is 1 hour, losing more than 1 hour of data is unacceptable.
Business Impact Analysis - Understanding which systems are critical and what downtime costs.
Service Level Agreements (SLAs) - Commitments to customers about availability and recovery.
Defining clear objectives guides recovery strategy.
Disaster Recovery Strategies
Different strategies suit different situations:
Backup and restore - Regular backups enable restoring from backups after failure. Slower but cost-effective.
Pilot light - Minimal live infrastructure running in alternate location. Quick activation but requires testing.
Warm standby - Replicated infrastructure running scaled-down, quickly scaled up during disaster.
Hot standby - Fully redundant infrastructure running in parallel. Most expensive but fastest recovery.
RTO and RPO requirements guide strategy selection.
Backup Strategies
Backups enable recovery:
Full backups - Complete data copies. Simple but requires significant storage.
Incremental backups - Only changed data since last backup. Efficient storage but restoration requires multiple backups.
Differential backups - Changed data since last full backup. Balance between efficiency and restoration simplicity.
Backup frequency - More frequent backups reduce data loss but increase backup load.
Backup testing - Regularly testing backups ensures they are valid when needed.
Backup Implementation
Implementing backups:
Backup storage - Backups stored separately from primary systems.
Geographic separation - Backups in different locations protect against regional disasters.
Encryption - Backups encrypted protecting sensitive data.
Retention policies - Keeping backups for sufficient time to detect issues.
Automation - Automated backup processes ensure consistency.
Replication
Replication enables faster recovery:
Database replication - Replicating databases to standby systems.
Asynchronous replication - Changes replicate asynchronously, minimal performance impact but potential data loss.
Synchronous replication - Changes replicated before acknowledging writes, zero data loss but higher latency.
Cross-region replication - Replicating to different regions for geographic redundancy.
Consistency verification - Ensuring replicated data remains consistent with primary.
Disaster Recovery Testing
Testing is essential:
Regular drills - Periodically simulating disasters and executing recovery processes.
Tabletop exercises - Team discussions of disaster scenarios.
Failover testing - Actually failing over to standby systems.
Recovery procedure validation - Verifying documented procedures work.
Metric tracking - Verifying recovery meets RTO and RPO objectives.
Testing reveals gaps before real disasters occur.
Cloud-Based Disaster Recovery
Cloud providers enable disaster recovery:
Multi-region deployment - Deploying across regions enables failover if region fails.
Automatic failover - Services automatically failover to alternate regions.
Managed backups - Cloud providers offer managed backup services.
Geographic redundancy - Automatic data replication across regions.
Disaster recovery as a service (DRaaS) - Third parties provide managed disaster recovery.
Cloud architecture simplifies disaster recovery compared to on-premise infrastructure.
Failover Processes
Executing failover:
Detection - Detecting that primary systems are unavailable.
Notification - Alerting teams of failure.
Decision-making - Deciding whether to failover.
DNS updates - Redirecting traffic to standby systems.
Data consistency - Ensuring standby systems have latest data.
Communication - Informing customers of situation.
Automated failover processes respond faster than manual processes.
Disaster Recovery Plans
Comprehensive plans guide response:
Documentation - Detailed procedures for various failure scenarios.
Responsibilities - Clear assignment of decision-making authority and responsibilities.
Contact information - Ways to reach team members during disasters.
Recovery procedures - Step-by-step instructions for recovery.
Communication templates - Pre-prepared messages for customers and stakeholders.
Timeline estimation - Expected durations for various recovery stages.
Written plans enable coordinated response.
Disaster Recovery at PixelForce
PixelForce designs applications with disaster recovery in mind. Multi-region AWS deployments enable failover if primary region becomes unavailable. Automated backups with geographic separation protect against data loss. Regular disaster recovery testing ensures we can recover within our commitments.
Business Continuity Planning
Broader than disaster recovery:
Critical functions identification - Understanding which functions are critical.
Alternative processes - Procedures for continuing critical functions during outages.
Supply chain resilience - Ensuring suppliers can support recovery.
Communication plans - Keeping customers informed during disruptions.
Regulatory compliance - Meeting regulatory requirements for resilience.
Business continuity planning addresses broader organisational resilience.
Insurance and Risk Transfer
Risk management approaches:
Cyber insurance - Coverage for cybersecurity incidents.
Business interruption insurance - Coverage for revenue loss during outages.
Property insurance - Coverage for physical infrastructure.
Liability insurance - Coverage for customer harm from outages.
Insurance transfers some risk to third parties.
Recovery Metrics
Monitoring recovery capability:
RTO adherence - Whether actual recovery meets target RTO.
RPO adherence - Whether actual data loss meets target RPO.
Recovery success rate - Percentage of recovery attempts that succeed.
Detection time - Time to detect failures.
Failover time - Time to complete failover.
Metrics guide continuous improvement.
Disaster Recovery Checklist
Key elements:
- RTO and RPO defined
- Recovery strategy selected
- Backup systems implemented and tested
- Replication implemented if needed
- Failover procedures documented
- Team trained and cross-trained
- Contact information current
- Regular testing scheduled
- Disaster recovery plan updated regularly
Conclusion
Disaster recovery planning is essential for organisations that must maintain availability despite catastrophic failures. By defining clear recovery objectives, selecting appropriate recovery strategies, implementing backups and replication, testing regularly, and documenting procedures, organisations minimise business disruption from disasters. In an era of increasing cyber threats and natural disasters, disaster recovery is not optional - it is essential.