EXERCISE
1Learn practical backup approaches that protect against data loss. Start simple, scale as needed.
How it works:
Day 0 (Sunday): Take complete backup of entire database. 100GB stored.
Day 1 (Monday): Backup only changes from Monday. Maybe 2GB of new/modified data.
Day 2 (Tuesday): Backup only Tuesday changes. Another 2GB.
Continue daily.
Total storage: 100GB (full) + 7 days × 2GB (incremental) = 114GB
Recovery: Restore full backup, then apply each incremental backup in order.
Storage efficient: Not storing full 100GB every day.
Recovery point: If database crashes Wednesday, you lose only Wednesday data. Tuesday backup available.
Acceptable loss: Most businesses can afford losing one day of data versus losing everything.
How it works:
Every Sunday, take complete snapshot of database regardless of size.
Why weekly complete backups matter:
Incremental backups can corrupt. If Monday incremental is corrupted, you cannot restore Tuesday onward.
Weekly complete backup is safety net. Even if daily incrementals fail, you have last Sunday full backup.
Example:
Week 1: Full backup Sunday (100GB)
Daily incrementals Monday-Saturday (2GB each)
Week 2: Full backup Sunday (105GB)
Daily incrementals Monday-Saturday
If Wednesday incremental corrupts: Restore Sunday full backup. Lose only 3 days instead of entire database.
The ultimate protection: Store backup in different geographic location.
Scenario: Your data center is in California. Earthquake destroys entire facility. Servers gone. Disks gone. Everything gone.
Without cross-region backup: Business ends.
With cross-region backup: Copy of database in Virginia data center. Switch to Virginia. Business continues.
Weekly process:
Bandwidth consideration: 30GB upload once per week is manageable.
Cost: Extra storage + bandwidth. Worth every penny.
Amazon RDS ( Service):
Offers automatic cross-region . Your database in us-east-1? Enable replica in eu-west-1.
AWS region failure: Happened in 2017. Multiple data centers down for hours.
Customers with cross-region redundancy: Switched regions. Stayed online.
Customers without: Complete outage. Lost revenue.
Local disk on same server: Fast but dangerous. Server dies, backup dies.
Separate backup server: Better. Database crashes, backup survives.
Cloud storage (S3, Google Cloud Storage): Excellent. Cheap, reliable, geographically distributed.
Multiple cloud providers: Paranoid level protection. AWS down? Backup on Google Cloud. Both down? Extremely unlikely.
How long to keep backups?
Daily incrementals: Keep 7 days. Older than week? Delete.
Weekly complete: Keep 4 weeks (one month).
Monthly archives: Keep 12 months (one year).
Balance: Storage cost vs recovery options.
Backup you never tested is worthless.
Horror story: Company had backups for years. crashed. Tried restoring backup. Backup corrupted. All backups corrupted. Backup process had bug nobody noticed.
Best practice: Quarterly backup restoration test.
If restore fails, fix immediately. Backup system is broken.
Pessimism wins: Assume disaster will happen. When? Unknown. Could be today.
Prepared businesses survive. Unprepared businesses become cautionary tales.
Backups are boring. Disasters are exciting in the worst way. Choose boring.
