How do I Activate/Deactivate the EWF (Enhanced write filter) on Windows 7?

Issue

File writes or program installation to the main drive of a Magelis iPC are not being kept before and after a restart because the disk volume is write-protected.

Product Line

Magelis iPC, HMIG5U, HMIG5U2, HMIG5U22, Harmony P6

Environment

Windows 7 Embedded

Cause

The main disk volume of the iPC is write-protected in order to maximize the life of the disk as well as ensuring the saved state of the disk for consistent behavior day-to-day for applications which need it (for example a factory HMI). This is done through a feature called the Enhanced Write Filter in Windows 7 (EWF) and the Unified Write Filter in Windows 10 (UWF)

Resolution

Verifying current state of EWF:

1. Click on the** Start** button on your PC.
2. Please now select the Run option and at the command prompt type** cmd** (make sure there's administrator rights... if not run as administrator)
3. You will now be presented with a black command prompt window and within this will need to type – ewfmgr c:
4. This will now return a series of results and will tell you the current state of the EWF.

The Windows Taskbar will also indicate the EWF status:

See the screenshot: "Windows Taskbar EWF State.png"

EWFMGR activate and deactivate commands to use:

To use any of the following commands then you will need to firstly navigate to the command prompt window with the following steps:

1. Click on the Start button on your PC.
2. Please now select the Run option and at the command prompt type cmd
3. You will now be presented with a black command prompt window and begin typing the following commands:

ewfmgr.exe c: -Enable

Activates the EWF from the DOS cmd prompt.

ewfmgr.exe c: -Disable

Deactivates the EWF from the DOS cmd prompt.

ewfmgr.exe c: -commitanddisable

Commits changes that exist in the RAM state to the drive, then deactivates the EWF from the DOS cmd prompt

The Graphical User Interface to Activate/Deactivate EWF can also be used (EWF Windows GUI.PNG):

1. Double-click on the padlock icon and the :Enhanced Write Filter: Overview” popup should appear.

2. Select the “C:” row.

3. Click on “Configure…”

4. Select “Disable”

5. Tick the “Commit” Checkbox

6. Click OK

7. Windows Restart windows from the Start bar.

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To Activate/Deactivate the UWF (Unified Write Filter) on Windows 10, please see this FAQ: https://www.se.com/us/en/faqs/FAQ000245569/

Released for: Schneider Electric Singapore