Original evidence
No initialization, formatting or write-back before the array state is recorded.
Before you rebuild, reset or swap a drive
Stop one bad step
before it costs the data.
Choose the symptom closest to what you see. Each guide starts with the actions that preserve the original disks and the array state.
Smoke, burning smell or extreme heat?
Prioritize personal and fire safety. Disconnect power when it is safe to do so.
HIGH-INTENT FAILURE GUIDES
What happened to the NAS?
REBUILD
RAID rebuild failed or stopped
Separate a stalled rebuild from an inactive or crashed array, and know when another attempt adds risk.
Open the guide →MULTI-DRIVEMultiple drives show warnings
Understand fault tolerance without assuming that RAID 5, RAID 6 or SHR makes another replacement safe.
Open the guide →PHYSICALThe NAS or hard drive is clicking
Distinguish normal seek noise from repeated hard clicks, grinding and symptoms that call for shutdown.
Open the guide →What these guides protect
Remaining drives
No repeated rebuild or full-disk test when another member may be failing.
Your decision
Clear thresholds for manufacturer procedures, stopping, or professional evaluation.
We do not diagnose hardware remotely or promise recovery. The technical references come from current manufacturer documentation; your exact model and firmware instructions take priority.