When Dell PERC detects a configuration mismatch, it offers two deceptively simple choices:
Import or Clear.
To the average administrator, that looks like progress.
To ADR, it’s the most dangerous prompt in the entire controller ecosystem.
An incorrect import merges outdated metadata into live parity maps; a clear erases configuration references that describe the entire array layout.
Both actions alter controller memory and write to disk—often before the operator realizes what was changed.
Every recovery that starts after one of these clicks takes ten times longer, because the original controller logic has been replaced by assumptions.
The Import / Clear Decision Explained
- Import tells the controller to trust the metadata it found on the drives, replacing whatever is stored in NVRAM.
- Clear tells it to erase the foreign metadata on the drives and retain the controller’s current map.
- Neither preserves the full truth. In hybrid events—where cache and disk disagree—both sides contain part of the valid geometry.
In real-world cases, one drive’s header may have correct parity rotation while another’s header contains the last known sequence number. Importing overwrites one; clearing deletes the other.
Risks by Action Type
| Action | Immediate Effect | Long-Term Consequence |
|---|---|---|
| Import | Writes controller’s chosen configuration table to all member disks. | Overwrites valid geometry if timestamps or controller IDs don’t match. |
| Clear | Deletes all foreign metadata and resets array association. | Removes layout evidence required for forensic mapping. |
| Force Online After Import | Commits partial parity maps to disk. | Creates silent corruption—filesystem mounts but data invalid. |
| Rebuild After Import | Recalculates parity over mismatched stripes. | Irreversible data loss across entire array. |