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KB ID: 6127

Product: WS5020 2016 Series | WS5020 IoT 2019 | WS5020 IoT 2025

TeraStation WS5020 Recovery Procedure

Last Updated: 05/04/2026

Critical Warnings
The recovery script targets Disk 0 exclusively.
All data on Disk 0 will be destroyed during this process.

1. Insert the Buffalo-supplied recovery USB into an available USB port on the NAS.

2. Power on the unit. At the splash screen, press F11 to enter the Boot Menu.

3. Choose your USB recovery media from the list and press Enter.

4. When the blue "Confirmation of starting Recovery" screen appears, press the physical Function button on the NAS front panel.
This will launch the Recovery process.

5. The system will automatically apply the Windows image.

Note: The unit will automatically shut down once the process is 100% complete. Remove the USB drive after shutdown.

6. To prevent the NAS from attempting to boot from the "ghost" OS remaining on Disk 1 (the former mirror), you must manually set the boot priority.

a. Power on the unit and enter the BIOS (Aptio Setup Utility).
b. Navigate to the Boot tab.
c. Set Boot Option #1 to Windows Boot Manager (P0:...) to ensure the fresh install on Disk 0 takes precedence.
d. Press F4 to Save & Exit.

7. Once Windows boots successfully:
a. You can go ahead and attempt to recover existing data from the Degraded Dynamic Array using Disk Management (diskmgmt.msc), and backup the data to other storage devices.
b. Or launch the Buffalo RAID Builder utility to recreate the system and data volumes.
Note: Using the RAID Builder will initialize all drives and erase all existing data. Only use this if you have already backed up your data or do not need it.