Functions
9.2 Enhanced Write Filter (EWF)
SIMATIC IPC427C
48 Operating Instructions, 04/2009, A5E02414743-01
9.2 Enhanced Write Filter (EWF)
Purpose and function
The EWF (Enhanced Write Filter) is a function that is only available with Windows
Embedded operating systems. It provides write protection that can be configured by the
user.
The Enhanced Write Filter allows you to boot Windows Embedded Standard 2009 from
write-protected media (such as CD-ROM), to write protect individual partitions and adapt the
performance of the file system to your needs (when using CompactFlash cards, for
example).
EWF can be used to minimize write access to Compact Flash cards. This is important
because the write cycles on Compact Flash cards are limited due to technical reasons. We
therefore recommend using EWF if you work with Compact Flash cards.
CAUTION
Activate only one write filter per partition - otherwise you may incur data loss.
Both EWF and FBWF are preinstalled in the SIMATIC IPC images.
Ensure that only one write filter is enabled on a partition, otherwise you may incur data loss.
Note
The Enhanced Write Filter is disabled by default for Windows Embedded Standard 2009.
After the operating system has been set up, you should back up your date and then enable
the EWF.
Set EWF
The EWFMGR.EXE program can be used to install, enable or disable the EWF. Use the
command prompt to call up the program. The following functions are available:
Function Command
Write-protect drive C: Switching on
ewfmgr c: -enable
Write-protect drive C: disable
(modified files are accepted)
ewfmgr c: -commitanddisable
Modified files on drive C: Accept
ewfmgr c: -commit
Display information about the EWF drive
ewfmgr c:
Display help
ewfmgr c: /h
Note
The EWF commands affecting the write protection do not become active until after the next
booting process.
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