Brand-specific RAID failure symptoms and system-level confusion decoded
When your system throws strange RAID messages, it can feel like something is wrong everywhere — the drives, the controller, the BIOS, the NAS, the OS.
But in reality, controller behavior is often the missing piece nobody explains.
You may see messages like:
- “foreign config”
- “missing virtual disk”
- “array degraded after reboot”
- “controller sees all drives but no volume”
- “virtual disk not presented”
These symptoms don’t always reflect drive failure.
Often the controller is confused, protecting data, or refusing to commit writes because something in its metadata does not match what it expects.
This section helps you identify controller-side problems, not drive problems — covering HP SmartArray, Dell PERC, LSI MegaRAID, Synology, QNAP, TrueNAS, and other common platforms.
Brand & System Triage Pages
- Dell PERC: Foreign Config Detected After Reboot
- HP SmartArray: Virtual Drive Missing After Power Loss
- HP Smart Array: RAID Controller Shows Drives — But No Logical Volume
- LSI MegaRAID: Rebuild Won’t Start — All Drives Healthy
- Synology: RAID Group Degraded — But No Drive Failed
- Synology NAS Says Healthy — But No Data Shown
- QNAP: Disk Missing After Firmware Update
- TrueNAS: Volume Won’t Mount After Drive Replaced
Technical Note TN-C1-001
Controller Metadata Behavior, Foreign Config States, and Virtual Disk Identity Failures
This foundational Technical Note explains how modern enterprise RAID controllers (Dell PERC, HPE Smart Array, LSI/MegaRAID, Synology, QNAP, TrueNAS, FreeNAS, and OpenZFS systems) protect arrays by refusing to present a logical volume when metadata no longer agrees. It documents why controllers enter Foreign Config, Virtual Disk Missing, and Rebuild Blocked states — and how topology drift, stale headers, and partial writes can break identity even when every disk appears healthy.
TN-C1-001 is the authoritative reference behind every Controller & System Triage page in this series.
- How RAID Controllers Store and Validate Array Metadata
- Why “Foreign Config” Appears After Power Loss or Drive Movement
- Virtual Disk Missing & Identity Drift After Header Mismatch
- Rebuilds That Won’t Start Even When All Drives Test Good
- Cache Flush, NVRAM Coherency, and Post-Event Topology Desync
- Slot Order, Identity Drift & Migration Conflicts
- Correct Forensic Triage Order Before Any Import, Clear, or Repair
Read the Full Technical Note TN-C1-001 →
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