Dell PERC Triage » Foreign Config After Reboot

Symptom / What You See

  • On boot or after a power event, controller shows Foreign Config Detected.
  • One or more members listed as Foreign or Unconfigured (Foreign).
  • Virtual Disk is missing, offline, or volumes appear RAW.
  • iDRAC or BIOS prompts to Import or Clear the foreign configuration.

This feels like a drive failure, but it’s usually a metadata epoch mismatch: the controller’s current view of layout and parity no longer matches what’s on the disks.

What It Means (Technical)

Dell PERC (LSI/MegaRAID lineage) writes configuration headers to each member. After certain events, those headers can be out of sync with the controller’s in-memory or NVRAM state:

  • Power loss / brownout during write-back cache activity
  • Firmware change or controller swap without a clean export/import
  • A member timed out and rejoined with stale or newer epoch than the set
  • Slot changes / backplane hiccups altering identity and order

The controller flags a Foreign set to protect data. If you import the wrong epoch, you can commit an incorrect layout that overwrites the last good parity.

What NOT To Do

  • Do not Import blindly. Importing a mismatched epoch can destroy the only intact parity history.
  • Do not Clear the foreign set to “start fresh.” That erases the evidence you need to reconstruct safely.
  • Do not Initialize or recreate the virtual disk. That writes new headers over recoverable metadata.
  • Do not Force Online members to make the count look right. Forcing the wrong disk corrupts parity.
  • Do not Swap controllers or shuffle drives between slots to “see if it works.”

One wrong write turns a recoverable event into permanent loss.

Safe Actions (Triage You Can Do)

  • Photograph the screens: PERC Foreign View, Virtual Disk configuration, and Physical Disk list.
  • Record bay order and serials exactly as they are now.
  • Capture metadata read-only from all members, including any marked Foreign.
  • Check logs for power anomalies, cache battery status, and link resets or timeouts.
  • Inspect pathing (backplane, cables, PSU rails). Reseat connectors only; do not move drives between slots.
  • Pause and escalate if member order, stripe size, rotation, or start offsets are uncertain.

If the system was healthy pre-event, clean recovery is likely when the current state is preserved.

Controller Clues (Helpful Observations)

  • Foreign view matches drive count but not order → identity drift; likely recoverable.
  • Multiple foreign sets across the same members → mixed epoch; careful selection required.
  • Virtual Disk shows Ready or Missing despite healthy disks → metadata conflict, not mechanical failure.
  • Cache/battery warnings around the event → high risk of incomplete writes and header desync.

How Professionals Recover This Case

  1. Clone first: image each member read-only to stabilized media.
  2. Interrogate headers across members to identify the correct epoch, stripe unit, parity rotation, and offsets.
  3. Resolve identity conflicts (slot vs. serial vs. header identity).
  4. Assemble virtually with verified member set and order; test parity consistency across stripes.
  5. Mount read-only and extract data; only then consider building replacement hardware.

This method avoids destructive imports while preserving the only accurate map of your data.

Real-World Insight

Foreign config after a power event is one of the most common PERC cases we see. Often, no disk is truly bad: one member briefly dropped and came back with a header that doesn’t match the others. Importing that “new” view commits the wrong geometry. Capturing current metadata and reconstructing the correct epoch restores access without a controller-led rebuild.

When To Escalate

  • You cannot confirm which epoch is correct.
  • Import prompts don’t match the last known layout.
  • Two or more members toggle between Foreign/Online/Missing.
  • Filesystem remains RAW after an attempted import or rebuild.
  • Any uncertainty about parity rotation or start offsets.

Get Help

Talk to an engineer before committing any writes. Provide screenshots, drive labels/serials, and a brief change history (power, firmware, hardware). We will validate the safe path and reconstruct the correct layout without risking parity.