ECC & Self-Healing
Reed-Solomon Error Correction
DodaZIP includes optional Reed-Solomon erasure coding that adds parity data to your archive. If parts of the archive become corrupted, DodaZIP can reconstruct the lost data from the surviving chunks and parity.
How It Works
Reed-Solomon encoding divides archive data into k data shards and computes m parity shards. The total archive is k + m shards. As long as at least k shards survive, the archive can be fully reconstructed.
Protection Levels
| Level | Parity Overhead | Tolerates Corruption Of |
|---|---|---|
| None | 0% | Nothing |
| Low | ~25% | Up to 20% of the archive |
| Medium | ~50% | Up to 33% of the archive |
| High | ~100% | Up to 50% of the archive |
When to Use ECC
- Cold storage — Archives stored on tape, optical media, or inexpensive cloud tiers are prone to bit rot
- Long-term archiving — Bit errors accumulate over years. ECC ensures your data stays recoverable
- Unreliable networks — Archives downloaded over unstable connections can suffer corruption
- Distribution — ECC lets recipients recover from partial download failures without re-downloading
Trade-offs
- Storage overhead — ECC parity data increases archive size by 25–100%
- Compression ratio — ECC is applied after compression, so overhead is on the compressed data (not the original)
- Speed — Encoding and decoding add computational overhead, roughly proportional to the parity level
Example
A 10 GB archive with Medium ECC (+50%) becomes 15 GB. If 3 GB become corrupted, DodaZIP reconstructs the missing data from the remaining 12 GB of valid content + parity. Without ECC, the entire 10 GB archive would be lost.