TN-R5-007 — Controller Automation as a Failure Accelerator
0. Purpose and Scope
This note documents how controller automation destroys recovery paths during degraded RAID 5 operation.
1. Automation Behaviors
Common automated actions include:
- Auto-rebuild
- Patrol read
- Background verify
- Cache policy changes
2. Automation Assumptions
Automation assumes parity correctness and stable disks.
In degraded RAID 5, these assumptions are unsafe.
3. Resulting Damage
Automation:
- Rewrites parity without validation
- Forces marginal drives offline
- Converts recoverable states into unrecoverable ones
4. Operational Guidance
Automation must be disabled before any recovery decision is made.