When dealing with disaster recovery, two key concepts define how well a system can recover: Recovery Point Objective (RPO) and Recovery Time Objective (RTO). Understanding these helps businesses plan for data loss and downtime effectively.
RPO and RTO Explained
- RPO (Recovery Point Objective): This determines how often backups are taken. The time between the last backup and a disaster represents the amount of data that could be lost. The lower the RPO, the less data loss your business will experience.
- Example: If backups are taken every 12 hours and a disaster occurs, you could lose up to 12 hours of data.
- RTO (Recovery Time Objective): This is the time taken to recover after a disaster. The lower the RTO, the faster you can resume operations.
- Example: If your RTO is 2 hours, your system should be fully operational within 2 hours after a disaster.
Backup and Restore (High RPO)
- This is the simplest disaster recovery method.
- On-premises: Large backups may require shipping data physically using tools like AWS Snowball.
- Cloud: Scheduled backups ensure data is available but recovery can be slow.
- Example: A company that takes nightly backups may lose an entire day’s data if disaster strikes before the next backup.
Pilot Light Approach
- A small version of your application is always running in the cloud.
- Useful for critical systems that need a faster recovery than full backup and restore.
- In case of disaster, the environment is quickly scaled up.
- Example: A bank keeps its transaction processing system active in pilot light mode so it can immediately recover.
Warm Standby
- The entire system runs in the cloud but on a minimum scale.
- During a disaster, it scales up to full production.
- Example: A retail company runs a minimal version of its website and scales up only when needed.
Multi-Site / Hot Site Approach
- It is the lowest RTO but very expensive.
- The full production environment is always running both on-premises and in AWS.
- If going fully cloud-based, AWS Multi-Region ensures redundancy.
- Example: A global e-commerce site runs production servers in multiple AWS regions, ensuring zero downtime.
DMS (Database Migration Service)
- Fast, secure, and resilient database migration.
- Keeps the source database active during migration.
- Supports homogeneous (e.g., Oracle to Oracle) and heterogeneous (e.g., SQL Server to Aurora) migrations.
- Uses CDC (Change Data Capture) for continuous replication.
- Requires an EC2 instance for replication tasks.
- For different database engines, AWS Schema Conversion Tool helps convert schemas.
- Multi-AZ ensures high availability by maintaining a standby replica in a different region.
- Example: A company migrating from MySQL to PostgreSQL uses DMS for seamless migration without downtime.
TL;DR
- RPO = How much data loss you can afford.
- RTO = How quickly you need to recover.
- Backup & Restore = Simple but slow recovery.
- Pilot Light = Keeps critical systems running for quicker recovery.
- Warm Standby = Full system running at minimal capacity scales up when needed.
- Multi-Site/Hot Site = Full-scale, real-time backup for zero downtime.
- DMS = Secure database migration with minimal disruption.
Planning your disaster recovery depends on how much downtime and data loss your business can handle!
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Cloud_Computing