## Backup Flow

How a backup job executes from trigger to completion

Backup Execution Flow
1
Trigger
Manual click or scheduled cron trigger fires
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2
Create Execution Record
Insert row into job_executions with status "pending"
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3
Connect to Source
Establish connection (local filesystem, SSH, or database)
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4
Determine Backup Strategy
Full backup OR incremental based on last successful backup
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5
Execute Backup
Transfer data, compress, encrypt (if enabled), calculate checksums
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6
Verify & Store
Verify checksum, store metadata in backups table, update execution status
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7
Cleanup & Retention
Apply retention policy, remove old backups, update storage stats

### Error Handling

- Connection failures: Retry 3x with exponential backoff, then mark as failed
- Partial backups: Mark as failed if any source file fails; keep partial for inspection
- Storage full: Check before starting, alert if < 10% free space
- Checksum mismatch: Delete corrupted backup, retry once, alert admin
- Concurrent jobs: Queue or cancel based on resource availability

### Extensibility Design

The system is designed for easy extension:

- Source adapters: Abstract base class for new source types (S3, Azure, etc.)
- Storage backends: Pluggable storage interface for cloud destinations
- Notification channels: Webhook, email, Slack plugins for alerts
- Compression algorithms: Configurable (gzip, bzip2, zstd, none)