Describe disaster recovery strategies
14 Communications Technology – Disaster Recovery Strategies
What is Disaster Recovery?
Disaster Recovery (DR) is the plan that keeps a network or system running when something bad happens – like a fire, flood, cyber‑attack, or power outage. Think of it as a “backup plan” for the whole IT infrastructure.
Key DR Concepts
- Recovery Point Objective (RPO) – The maximum amount of data loss you can tolerate. Example: RPO = 4 h means you can lose up to 4 hours of data.
- Recovery Time Objective (RTO) – The maximum time you can afford for the system to be down. Example: RTO = 2 h means the service must be back online within 2 hours.
- Fail‑over – Automatically switching to a backup system when the primary fails.
- Fail‑back – Switching back to the primary system once it’s repaired.
Common Disaster Recovery Strategies
- Full Backup – Copy everything. Fast recovery but expensive and time‑consuming.
- Incremental Backup – Only copy changes since the last backup. Saves space and time.
- Continuous Data Protection (CDP) – Every change is instantly backed up. Best RPO but costly.
- Replication – Duplicate data to a remote site in real time. Good for RTO and RPO.
- Cloud‑Based DR – Use a cloud provider’s infrastructure as a backup site. Flexible and scalable.
Analogy: The “Backup Backpack”
Imagine you’re going on a school trip. Your primary backpack holds all your books and snacks. If it breaks (a disaster), you have a backup backpack with a spare set of books and snacks. The RPO is how many pages you can lose before you’re stuck, and the RTO is how long it takes to switch to the backup backpack and keep going.
Choosing the Right Strategy
Use the Recovery Matrix to decide which strategy fits your needs.
| Strategy | RPO | RTO | Cost |
|---|---|---|---|
| Full Backup | Hours to days | Hours to days | High |
| Incremental | Minutes to hours | Hours | Medium |
| CDP | Seconds to minutes | Minutes | Very High |
| Replication | Seconds to minutes | Minutes | High |
| Cloud‑Based DR | Seconds to minutes | Minutes | Medium to High |
Exam Tip: “What would you recommend?”
When asked to choose a DR strategy, start by stating the business requirements (RPO, RTO, budget). Then match those to the table above. Always justify your choice with at least one advantage and one limitation.
Testing & Maintenance
- Schedule regular drills (e.g., quarterly) to practice fail‑over.
- Keep a DR checklist and update it after each test.
- Use simulation tools to verify backup integrity.
- Document contact lists for the recovery team.
Exam Tip: “Explain why testing is essential.”
Answer: Testing confirms that backups are usable, that recovery procedures are clear, and that staff know their roles. It also identifies gaps before a real disaster.
Summary Checklist (for the exam)
- Define RPO and RTO.
- Identify suitable backup types.
- Explain fail‑over and fail‑back.
- Discuss the pros/cons of on‑prem vs. cloud DR.
- Outline a testing schedule.
- Provide a clear justification for your chosen strategy.
Good luck! Remember: A solid DR plan is like a safety net that keeps the network from falling when the unexpected happens. 🚀
Revision
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