Verify DirectStorage BypassIO in Regedit

DirectStorage utilizes BypassIO on Windows 11 to dramatically reduce storage latency and CPU overhead by routing game data directly from NVMe storage to the GPU. This article outlines the steps to navigate the Windows Registry Editor (Regedit) to verify your storage stack configuration, inspect filter drivers, and determine the BypassIO compatibility states on your system.

Step 1: Open the Registry Editor

  1. Press Windows Key + R to open the Run dialog.
  2. Type regedit and press Enter.
  3. Click Yes if prompted by User Account Control (UAC).

Step 2: Navigate to the FileSystem Registry Key

The Windows file system stores core driver flags and file system compatibility settings under the control branch:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem

Inspect the values in the right pane to verify core file system operational parameters related to storage throughput and I/O handling.

Step 3: Check Disk Class Filter Drivers

BypassIO requires that no incompatible third-party filter drivers attach to the storage stack. Incompatible filters will cause Windows to fall back to the standard I/O path.

  1. In the Registry Editor, navigate to:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4d36e967-e325-11ce-bfc1-08002be10318}

  2. Check the following multi-string values:

    • UpperFilters
    • LowerFilters

  3. Review the drivers listed inside these keys. Antivirus, disk encryption, or legacy backup software filters present here can disable BypassIO support if they lack the SUPPORTED_FEATURES_BYPASS_IO flag.

Step 4: Verify Storage Controller and Driver Configurations

DirectStorage requires standard NVMe drivers or controller drivers that implement BypassIO protocols.

  1. Navigate to:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\stornvme

  2. Verify the Start DWORD value is set to 0 (indicating the native Microsoft NVMe driver is set to boot-start).

  3. If using proprietary storage controller drivers (e.g., Intel RST, Samsung NVMe), inspect the corresponding driver keys located under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ for driver health and configuration parameters.

Step 5: Understand BypassIO Registry Status Flags

When Windows queries a volume for BypassIO, it evaluates the volume against known internal states: