Rebuild Started — Now RAID Is Gone?
When a “Fix” Makes the Array Disappear
You selected the failed drive.
You clicked Rebuild.
Everything looked normal—until suddenly the entire RAID 5 volume vanished.
No virtual disk.
No mount.
Just a blank list where the array used to be.
This doesn’t mean your data evaporated.
It means the controller detected something unsafe mid-rebuild and hid the array instead of risking corrupted parity.
That silence is protection, not destruction.
What You See
- You initiated a rebuild and the controller accepted it
- Midway (or immediately), the virtual disk disappears
- Controller shows: Missing, Not Found, or No VD Present
- All drives still show Online, Unconfigured Good, or Ready
- Logs show:
- “incomplete configuration”
- “VD metadata invalid”
- “aborted background init”
- “foreign configuration found”
Why It Happens
1. A Survivor Hit a Latent Sector Error Mid-Rebuild
RAID 5 can tolerate exactly one member failure.
If any surviving disk encounters an unreadable sector during parity rebuild, the controller must stop immediately.
Ref: TN-R5-001 §3 (LSE exposure during rebuild)
2. Metadata Epoch Mismatch Was Detected
If cached metadata didn’t match on-disk signatures, the rebuild step triggered a safety lockout.
Ref: TN-R5-001 §4, §6
3. Write-Modify-Write Cycle Failed
RAID 5’s penalty cycle stresses the remaining disks.
If parity cannot be safely written, the controller hides the VD to prevent further corruption.
Ref: TN-R5-001 §1 (write penalty), §3
4. Replacement Drive Introduced Conflicting Metadata
If the new drive contains outdated RAID headers or unexpected signatures, the controller may invalidate the current config.
Ref: TN-R5-001 §4
5. Background Initialization Collided With Live Data
A partial background init can overwrite filesystem metadata and force the array offline.
Ref: TN-R5-001 §6
What NOT To Do
- Do NOT attempt another rebuild
- Do NOT force the array online
- Do NOT clear the virtual disk
- Do NOT remove or reshuffle drives
- Do NOT initialize the array “just to see if it comes back”
Each of those steps permanently overwrites evidence needed to restore the original layout.
What You CAN Do
- Stop all write activity immediately
- Clone all members sector-by-sector (failed, surviving, and replacement)
- Export controller logs and configuration
- Capture controller cache/NVRAM state before powering down
- Validate per-drive metadata signatures and timestamps
- Identify the exact stripe where the rebuild stalled
- Reconstruct the prior layout using parity-map comparison, not controller assumptions
With correct evidence, the array can often be rebuilt virtually—even when the controller refuses to mount it.
Diagnostic Overview
- Array Type: RAID 5 — Single Parity Set
- Controller State: Rebuild Initiated / Virtual Disk Missing
- Likely Cause: Latent Sector Error or Metadata Epoch Conflict During Rebuild
- Do NOT: Force Online, Retry Rebuild, or Initialize the Array
- Recommended Action: Clone All Members, Export Logs, Validate Metadata, Perform Offline Parity Reconstruction
RAID Triage Center – RAID 5 Triage – RAID 5 Technical Notes