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How do I enable and disable the EWF (Enhanced write filter) on Windows 7 Embedded iPC?

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


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 behaviour day-to-day for applications which need it (for example a factory HMI). This is done through a feature called the Enhanced Write Filter (EWF).


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 theres 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 enable and disable 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 

Enables the EWF from the DOS cmd prompt.

ewfmgr.exe c: -Disable

Disables the EWF from the DOS cmd prompt.

ewfmgr.exe c: -commitanddisable

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

 

The Graphical User Interface to Disable/Enable 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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