Disaster Recovery
Disaster recovery plans and implements the procedures for restoring IT systems after a catastrophic failure: natural disaster, cyberattack, or major outage. It defines recovery objectives, replication strategies, failover sites, and the testing that proves recovery actually works under pressure.
itPlatform engineering and SRE | OpenSkills.info
Intro
Disaster Recovery
Disaster recovery is the work of restoring technology services after a severe disruption. The disruption might destroy infrastructure, corrupt data, disable a region, or make a primary site unusable.
Your goal is not to predict one dramatic event. Your goal is to preserve the business outcomes that depend on technology when normal operating assumptions fail.
That makes disaster recovery broader than keeping a backup. A usable recovery capability combines priorities, people, procedures, data, infrastructure, communications, and tests.
Start with business impact
A business impact analysis identifies the processes a system supports, their dependencies, and the harm caused by downtime or data loss. It gives you an order of recovery instead of a flat list of "critical" systems.
Use the analysis to answer four questions:
- Which business process must return first?
- Which applications, data, identities, networks, facilities, and suppliers support it?
- How much service interruption can the process tolerate?
- How much recent data can the process lose?
The answers produce recovery requirements. They should come from business owners and technical owners together. A technically impressive recovery design is still wrong if it restores the wrong service first.
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Sources
- https://csrc.nist.gov/pubs/sp/800/34/r1/upd1/final
Supports
- Official status, scope, history, and purpose of NIST SP 800-34 Revision 1
- Availability of business impact analysis and contingency-plan templates
- Relationship of contingency planning to resilience, risk management, and incident response
- https://nvlpubs.nist.gov/nistpubs/legacy/sp/nistspecialpublication800-34r1.pdf
Supports
- Contingency planning as coordinated recovery of systems, operations, and data after disruption
- Seven-step planning process covering policy, business impact analysis, controls, strategy, plans, testing, and maintenance
- Business impact analysis, maximum tolerable downtime, recovery time objective, and recovery point objective
- Recovery priorities, dependencies, alternate processing, backup, and recovery strategies
- Activation and notification, recovery, and reconstitution phases
- Roles, activation criteria, outage assessment, ordered procedures, validation, and return to a known state
- Checklist, tabletop, simulation, parallel, full-interruption, and full-recovery test concepts
- https://csrc.nist.gov/CSRC/media/Projects/risk-management/800-53%20Downloads/800-53r5/SP_800-53_v5_1-derived-OSCAL.pdf
Supports
- Contingency plan ownership, coordination, distribution, review, protection, and maintenance
- Testing plan effectiveness and readiness, reviewing results, and initiating corrective action
- Alternate processing and storage sites, capacity planning, system backup, and recovery
- Test methods from walk-through and tabletop exercises through simulations and full recovery
- https://docs.aws.amazon.com/whitepapers/latest/disaster-recovery-workloads-on-aws/disaster-recovery-workloads-on-aws.html
Supports
- Disaster recovery as preparation for and recovery from a business-impacting workload disruption
- Relationship among business continuity, high availability, RTO, RPO, detection, and testing
- Cloud-provider features as inputs to workload recovery design rather than a complete plan
- https://docs.aws.amazon.com/whitepapers/latest/disaster-recovery-workloads-on-aws/disaster-recovery-options-in-the-cloud.html
Supports
- Backup and restore, pilot light, warm standby, and multi-site active-active recovery patterns
- Cost, complexity, standby state, and recovery-speed tradeoffs among patterns
- Need to recover data, infrastructure, configuration, application code, and capacity
- Regular assessment and testing against RTO and RPO
- https://learn.microsoft.com/en-us/azure/reliability/concept-business-continuity-high-availability-disaster-recovery
Supports
- Distinction among business continuity, high availability, and disaster recovery
- RTO as acceptable downtime and RPO as acceptable data loss, set for workload flows
- Cost and difficulty of near-zero recovery objectives
- Need for documented and testable recovery plans, communications, escalation, and service guidance
- Separate backup locations, restore testing, integrity checks, and alignment of backup intervals with RPO
- Disaster scenarios including infrastructure loss, human error, data corruption, and security incidents