Write Filters – share your experience with us
I'm a program Manager with the Windows Embedded Standard team working on the write filters – Enhanced Write Filter (EWF), File Based Write Filter (FBWF), and Registry Filter. I have been with Microsoft for almost 9 years, but just joined the Embedded team last year to work on the next version of Embedded systems based on Windows 7 codename 'Quebec'.
Write filters are part of the Embedded Enabling Features (EEFs) that enable the Embedded Windows community to protect their disks. They bring a wide variety of benefits including system resilience and reliability, stateless device operation, fast reboot capabilities with Hibernate Once Resume Many (HORM), and reducing wear on flash devices. The Disk protection in Windows Embedded Standard more than just a useful feature blog provides an overview of the write filters and corresponding benefits. Additionally, the write filters provide configuration and management utilities both at image creation and runtime. The Managing Disk Protection blog provides an overview for both configuration and runtime management. On the other hand, the great benefits of these features sometimes come at a cost, as they may interfere with the functionality of some other feature in the system especially those that require persistent write to the disk; servicing is a classical example as you currently cannot service a system that is protected by a write filter, unless you turn off the filter before servicing then turn it on again after you are done.
That said, we want to hear back from you about your experience, scenarios, pain points, and suggestions for the write filters. Your feedback is essential to direct our design more towards your scenarios and adapt our development to fulfill your requirements. Although I can't commit to accommodating all suggestions, issues and/or problems in our upcoming release, I'll make sure that this feedback becomes part of our core requirements and design considerations for subsequent releases.
Thank you for reading my first posting and I’m looking forward to having useful postings and productive discussions on this blog.
Comments
- Anonymous
February 09, 2009
The comment has been removed - Anonymous
February 23, 2009
Hi Daniel, Thank you for providing this valuable feedback. I wanted to get some clarification on a couple of points from your comments. Thanks.
- a service to control the overlay. It should do some configurable tasks on low memory. e.g. reboot Would an interface (API) be enough for this purpose? This way we are giving OEMs the flexibility to create their own applications according to their actual need. OR are you looking for a runtime app/service? If so, how would you like it to operate e.g. notify user, reboot…etc? Should it be configurable at runtime or just during image creation?
- a service or change of the interface to allow non admins to commit some files (e.g. via context menu in Explorer) Would you please elaborate on this scenario? I would be more in favor of using the exclusion list than allowing non-administrators to commit files in different parts of an FBWF protected system. This way we can limit non-admins access to only pre-specified set of files/directories (which are within their exclusion list).
- Registry Filter is nearly useless, because it starts to late. Try to add TCP/IP settings to the RegFilter. It's mere chance which settings will be used. True. The registry filter facilitates persisting specific registry keys – mainly two registry keys – that involve client/server interaction. The current architecture is not meant to save system configuration. So, this functionality is not supported by Microsoft, so it is up to the user to verify whether or not their registry keys would persist. To change system configuration, you need to disable FBWF, make your changes and then enable FBWF. Please let me know if I’m missing your ask here.
Anonymous
February 23, 2009
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March 11, 2009
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May 20, 2009
my problem is that i have industrial PC which run embedded XP as operating system, now i want to insatall a VC6 based application on that computer, when i click the setup file of the application a message appear "NOT A VALID WIN32 APPLICATION". Please help me for the proper installation of the application on the computer.Anonymous
July 09, 2009
Hi we are using ewf with regitry filters I have coonfigured them as per instructions but cannot get them to work. In the ocmponent dependencies list its says FAT does this mean ntfs isn't supportedAnonymous
July 09, 2009
NTFS is supported. Can you be more specific about what didn't work exactly? Which EWF Mode are you using? Did you add your partitions in Target Designer? If you are using Disk or RAM mode, did you have unpartitioned space for EWF volume? Providing more information would help us making better diagnostics of the problem.Anonymous
July 09, 2009
Saleem, If the OEM who created the embedded image did not include the correct dependenciescomponents in the image then the installation will fail or the app will not run. You need to work with the OEM -they own the image and, as every image is custom, only they know what features they included in it. The OEM may aso not support any changes to the device. LyndaAnonymous
August 16, 2009
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August 17, 2009
You might want to post these kinds of questions to the forum instead- http://social.msdn.microsoft.com/Forums/en-US/category/embeddedwindows/Anonymous
January 18, 2010
I am want to know how to use fbwf without the need of rebooting.Currently the process is disable,reboot,install,enable and finally reboot. I want to remove the two rebooting stages in this and save disk in the volume.Anonymous
January 19, 2010
Hi, Would you please help me understand your ask - Are you asking about servicing (installing updates) or regular writes to the system?Anonymous
January 19, 2010
My question is related to insalling updatesAnonymous
January 20, 2010
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June 09, 2010
When it will be implemented EWF in disk mode for Windows 7 (32bit/64Bit)?Anonymous
June 28, 2010
Hi, I am using EWF and HORM. I have a protected System Drive and an un-protected data drive both are NTFS patitions. From time to time I am still having issues with corruption on the data drive. I am not sure what is causing it and it is pretty rare (suspect power down at the wrong time). The problem is once the data partition is corrupted I can't seem to fix it without disabling HORM and EWF. And forcing and using chkntfs d: /c to force a check on next boot. If try chkdsk d: /f (I get error saying type of file system is ntfs. Chkdsk is not available for NTFS drives). Is there another way to repair the ntfs partition without disbaling HORM & EWF or should I be using FBWF on the data drive, would this stop potential corruption? Also as I side note : Does the Regfilter option work okay with an HORM enabled system?Anonymous
August 31, 2010
Hi, I would like to know how to successfully install a service when FBWF is enabled. When EWF is enabled, after the service is installed i commit the protected volume and reboot. This way all the files, registry settings and the service application persist. In the case of FBWF, i'm only able to commit the files not the registry settings and the service application. Also, is there any way by which i can add a key in the MonitoredKeys and make it persist while FBWF is enabled? Thanks.Anonymous
August 31, 2010
How to persist data in the registry in between reboots when FBWF is enabled?Anonymous
October 10, 2010
We re using, FBWF in XPe, installed on a CF-Card. What we really miss is a possibility to notify the user, wehne ver he does changes that will be lost after reboot (say generate a new file in a non-write-through folder). Is there any possibility to do this? Kind regards, WolfgangAnonymous
October 19, 2010
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November 29, 2010
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December 22, 2010
Hi zigdong, Would you be able to share 'diskmon' logs with us? The logs might help us better investigate this issue. Thanks, Abdelkader