Manual driver injection

Part of the restore process includes running HIR (Hardware Independent Restore) process which detects and loads common drivers to allow the system to be booted in the new environment. Some environments, target systems, and source images may need additional drivers for full functionality post restore. This is most common with restores to physical machines with unique hardware configurations.

Environment

  • Datto Unified Backup

Overview

Restoring to similar hardware to the original host can limit the amount of driver changes and possible incompatibilities during the restore process. This is also why it is recommended when restoring a virtual machine to use the same configuration for the new virtual machine, to not introduce unnecessary variables and risks during the restore. During the restore to new hardware (or a new virtualized environment) changes can often include but are not limited to:

  • Storage controllers (IDE, SATA, SCSI, NVMe)

  • Network adapters are replaced or virtualized

  • Chipset and HAL differences

If critical drivers—especially storage controller drivers—are missing or disabled, the system may fail to boot (commonly resulting in INACCESSIBLE_BOOT_DEVICE errors on Windows systems).

Some of the most common driver-related issues that could happen post restore that wouldn't prevent booting include:

  • Missing network connectivity

  • Poor performance

  • Unknown devices in Device Manager

To check for unknown or malfunctioning devices:

  1. Open Device Manager on the newly restored system.

  2. Look for yellow exclamation marks or "Unknown" devices.

  3. Right-click device in question.

  4. Select Update Driver.

  5. Select either:

    • Browse my computer for drivers, then point to the driver folder.
    • Search automatically for updated driver software.

  6. After migration, hidden devices from old hardware can sometimes cause conflicts. In Device Manager, select View, then Show hidden devices.

  7. Remove grayed-out devices (especially NICs and storage).

  8. If you restored to a virtual environment, install appropriate tools for the host:

    • VMware Tools
    • Hyper-V Integration Services
    • VirtualBox Guest Additions

  1. Boot into Recovery Environment using one of the following:

    • Windows Installation Media (ISO/DVD/USB)
    • WinPE (Windows Pre-installation Environment)

  2. Select Repair your computer, then Troubleshoot, then Command Prompt

  3. In Command Prompt, run:

    diskpart
    list volume

  4. Identify the correct Windows partition (it may not be C: in recovery mode).

  5. Assign a letter if needed:

    select volume X
    assign letter=D
    exit

  6. Ensure you have the extracted driver files (.inf, .sys, .cat) for the hardware that the image was restored to, especially for the storage controller.

  7. Place them on another attached media, such as:

    • USB drive
    • Secondary disk
    • Mounted ISO

  8. Use dism to add the driver(s) needed to the system.

    dism /image:<volume>:\ /add-driver /driver:<DriverLocation>\ /recurse

    Where:

    <volume>:\ = offline Windows installation, in this example we set the volume to D:\

    <DriverLocation> = location of extracted drivers, in this example they are located in a Drivers folder, on a USB labeled E.

    EXAMPLE  dism /image:D:\ /add-driver /driver:E:\Drivers\ /recurse

  9. If the drivers exist but are disabled, they can be loaded with regedit.

    regedit

  10. Navigate to: HKEY_LOCAL_MACHINE

  11. Load hive:

    File > Load Hive

  12. Open: D:\Windows\System32\Config\SYSTEM

  13. Name it: OfflineSystem

  14. Navigate to: HKEY_LOCAL_MACHINE\OfflineSystem\ControlSet001\Services

  15. Locate relevant driver (e.g., storahci, nvme, lsi_sas, etc.).

  16. Confirm that it is set to start, and update it if not:

    Start = 0

  17. Unload the hive when you are done.

  18. Restart the system.