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A senior database administrator at a global financial services firm faces a critical decision. Their 15 TB trading database requires:
Which backup strategy meets all these requirements? A single backup type cannot satisfy everything. The answer lies in understanding how different backup types complement each other and designing a holistic strategy that leverages the strengths of each.
This page synthesizes everything we've learned about full, incremental, and differential backups into a comprehensive comparative framework.
By the end of this page, you will have a complete understanding of how full, incremental, and differential backups compare across all critical dimensions, when each backup type is optimal, how to combine backup types into coherent strategies, and real-world strategy patterns used by enterprise organizations.
Let's begin with a comprehensive side-by-side comparison that captures the essential characteristics of each backup type.
| Characteristic | Full Backup | Incremental Backup | Differential Backup |
|---|---|---|---|
| Data Captured | Entire database | Changes since last backup (any type) | Changes since last full backup |
| Backup Size | ~100% of DB size | ~1-5% of DB size (daily) | Grows daily: 1% → 30%+ |
| Backup Speed | Slowest | Fastest | Medium (grows over time) |
| Storage Requirement | Highest | Lowest | Medium |
| Recovery Speed | Fastest | Slowest (chain dependent) | Fast (2 files) |
| Recovery Complexity | Simplest (1 file) | Complex (N files in order) | Simple (2 files) |
| Dependency | None - self-contained | All prior backups in chain | Only the base full backup |
| Failure Impact | Isolated to that backup | Cascade - breaks all subsequent | Isolated to that differential |
| Point-in-Time Recovery | To backup time only | To any logged transaction | To backup time (+ logs) |
| Typical Frequency | Weekly/Monthly | Hourly/Daily | Daily |
Notice that no backup type excels across all dimensions. Full backups are simplest to recover but most expensive to create. Incrementals are most storage-efficient but most complex to recover. Differentials split the difference. The 'best' choice depends entirely on your priorities.
Understanding how backup size evolves over time is crucial for capacity planning. Let's visualize a week's worth of backups under each strategy for a 1 TB database with 2% daily change rate.
| Strategy | Weekly Backup Data | Files to Restore Saturday's State | Restore Complexity |
|---|---|---|---|
| Daily Full | 7,000 GB (7 × 1 TB) | 1 file | Simplest |
| Full + Incremental | 1,120 GB (1 TB + 6 × 20 GB) | 7 files (in sequence) | Most Complex |
| Full + Differential | 1,370 GB (1 TB + growing diffs) | 2 files | Simple |
Storage Efficiency Rankings:
Recovery Simplicity Rankings:
The true test of any backup strategy is recovery. Let's analyze how each strategy performs in various recovery scenarios.
Scenario: On Saturday at 10 PM, the database server suffers complete storage failure. You need to restore to the most recent backup.
Full Backup Strategy:
Incremental Strategy:
Differential Strategy:
For fastest recovery from complete loss, daily full backups win—if you have the storage. Differential is a close second. Incremental is slowest due to chain application.
Backup strategy decisions should be informed by comprehensive cost analysis that considers storage, operations, and risk.
| Cost Category | Daily Full | Weekly Full + Inc. | Weekly Full + Diff. |
|---|---|---|---|
| Storage (TB) | 150 TB | 16 TB | 28 TB |
| Storage Cost/Month (@$0.02/GB) | $3,000 | $320 | $560 |
| Backup Time/Day | 8 hours | 30 minutes | 30 min → 2 hours |
| Recovery Time (worst case) | 8 hours | 12 hours | 9 hours |
| Recovery Complexity | Low | High | Low |
| Failure Risk | Isolated | Cascading | Isolated |
| Operational Overhead | Low | Medium | Low |
Hidden Costs to Consider:
Network Bandwidth:
Operational Risk:
Opportunity Cost:
If your hourly business loss during downtime is $10,000, and incremental recovery takes 4 hours longer than differential, that's $40,000 in potential additional downtime per incident. Factor this into your cost analysis.
Use this decision framework to guide your backup strategy selection based on your specific requirements and constraints.
| If Your Priority Is... | Primary Strategy | Secondary Strategy |
|---|---|---|
| Fastest possible recovery | Daily Full | Differential + Logs |
| Minimum storage cost | Weekly Full + Daily Incremental | Compression + Dedup |
| Simplest operations | Daily Full or Differential | Avoid long incremental chains |
| Point-in-time recovery | Any + Transaction Log Backups | Continuous log shipping |
| Maximum reliability | Differential + frequent verification | Multiple copies, multiple locations |
| Large databases (50+ TB) | Incremental with synthetic full | Parallel backup streams |
Real-world backup strategies rarely use a single backup type in isolation. Here are proven patterns used by enterprise organizations.
The GFS rotation scheme is a time-tested strategy for balancing protection with storage efficiency.
Structure:
Schedule Example:
Mon-Sat: Incremental/Differential backup
Sunday: Weekly Full backup (kept 4 weeks)
First-of-Month: Monthly Full (kept 12 months)
January 1: Yearly Full (kept 7 years)
Benefits:
Storage Calculation (1 TB database):
Here are proven backup strategy templates for common scenarios. Adapt these to your specific requirements.
| Scenario | Full Backup | Differential/Incremental | Log Backup | Retention |
|---|---|---|---|---|
| Small Business DB (<100 GB) | Daily | Not needed | Every 4 hours | 30 days |
| Mid-size OLTP (100 GB - 1 TB) | Weekly | Daily Differential | Hourly | 30 days + monthly archives |
| Large OLTP (1-10 TB) | Weekly | Daily Incremental | Every 15 minutes | GFS retention |
| Data Warehouse (>10 TB) | Monthly | Weekly Differential + Daily Inc. | Not applicable* | GFS + yearly |
| High-Availability (24/7 critical) | From replica: Weekly | Daily Differential | Continuous (log shipping) | 30 days + compliance |
| Compliance-Heavy (Finance/Healthcare) | Weekly + Quarterly archive | Daily Differential | Every 15 min | 7 years encrypted |
Data warehouses often use bulk-logged or simple recovery models where transaction log backups are not applicable or not used for recovery.
Template A: Standard OLTP Database (1 TB)
Schedule:
- Sunday 2 AM: Full Backup
- Mon-Sat 2 AM: Differential Backup
- Every hour: Transaction Log Backup
Retention:
- Daily differentials: 7 days
- Weekly fulls: 4 weeks
- Monthly fulls: 12 months
RPO: 1 hour (worst case)
RTO: 4 hours (estimated)
Template B: Large Enterprise Database (50 TB)
Schedule:
- Week 1 Sunday: Full Backup (from replica)
- Daily 1 AM: Incremental Level 1
- End of week: Synthetic Full creation
- Every 15 min: Log backup to DR site
Retention:
- Incrementals: 7 days
- Synthetic Fulls: 4 weeks
- Monthly archives: 7 years
RPO: 15 minutes
RTO: 8 hours
Choosing the right backup strategy is a multi-dimensional decision that balances competing requirements. Let's consolidate the key insights:
What's Next:
Now that we understand how backup types compare and combine, the final page addresses Strategy Selection—diving deeper into the decision-making process for choosing and implementing backup strategies tailored to specific organizational requirements.
You now have a comprehensive understanding of how full, incremental, and differential backups compare across all critical dimensions. This knowledge enables you to evaluate existing backup strategies, identify gaps, and design optimal approaches for diverse scenarios.