TN-R5-008 — Software Reconstruction vs. Hardware Rebuild
0. Purpose and Scope
This note explains why software-based reconstruction is required for RAID 5 recovery.
1. Hardware Rebuild Characteristics
- Performs writes immediately
- Assumes parity correctness
- Cannot roll back changes
2. Software Reconstruction Characteristics
- Read-only analysis
- Deterministic modeling
- Reversible decision paths
3. Why Imaging Comes First
Imaging preserves:
- Original member state
- Evidence of failure
- Recovery options
Rebuilds erase this information.
4. ADR Recovery Principle
Reconstruction precedes rebuild.
Rebuilds are performed only after data is recovered.