File write filter

You can do this in one of the following ways:. You can change these settings after you turn on UWF if you want to. For example, you can move the page file location to an unprotected volume and re-enable paging files. In this case, you must manually turn off the other features and services if you want to increase the performance of UWF. All configuration settings for UWF are stored in the registry. UWF automatically excludes these registry entries from filtering.

UWF maintains configuration settings in the registry for the current session and for the next session after a device restart. Static configuration changes do not take effect until after a device restart, and these changes are saved in the registry entries for the next session.

Dynamic configuration changes occur immediately and persist after a device restart. Skip to main content. This browser is no longer supported. Write filters allow the writes to be discarded or committed to the physical volume later either directly or when another action causes the changes to be committed.

As this minimizes writes to a specified hard disk, the write filters have become popular as a way to decrease wear of solid state drives on embedded devices. Because write filters allows the run-time image to maintain the appearance of a writable run-time image without committing the changes to the storage media, you can reduce the number of disk writes on your devices.

In addition, you can use write filters as an easy to way return operating system images to a known state, to reduce help desk and administrative overheads that might otherwise be required to check for and remediate configuration drift. When write filters are enabled, you cannot persist or commit any changes that you have made. For example, if you have installed an application, the installation will not persist after you restart the device.

Because of this behavior, we need to manage these write filters if changes and applications must persist after a restart, and this can be challenging for administrators. It involves the following steps:.

Before Configuration Manager SP1, administrators had to devise their own methods to achieve the required steps.

We wanted to help make this easier for you, so that you could continue to have all the advantages of write filters but manage these devices similarly to how you manage other devices on the network. As we looked at extending Configuration Manager to better manage these write filter-enabled devices, we had the following design goals and assumptions in mind:.

Building on our design intentions and assumptions, these three main areas encapsulate the changes we made to help you manage write filter-enabled devices. Configuration Manager SP1 lets you force the persistence of an installation that you want to commit to the disk. However, we also wanted to accommodate administrators who require business continuity and cannot immediately restart the device. To accommodate both requirements, Configuration Manager lets you either persist the change immediately, or temporarily write it on the overlay and then opportunistically persist it later when another change is made that is tagged to be persisted.

You make this choice when you create a deployment. On the User Experience page of the Deploy Software Wizard, select the check box Commit changes at deadline or during a maintenance windows requires restarts , as shown in the following screenshot. If you want the deployment to persist, make sure that this check box is selected. By default, this check box is selected, with the exception of the Automatic Deployment Rule Wizard when you select the Definition Updates template for Endpoint Protection.

If you do not want to initiate a write filter restart to persist this content, make sure this check box is not selected. When the check box is not selected, you will not initiate a restart, but the deployment will be applied to the overlay at the deadline schedule, or during a configured maintenance window. The drawback with this choice is that your installation might not persist after a restart. For applications, software updates etc. Obviously, this introduces a delay and there is a further delay because the device must restart each time before the required changes are re-applied to the overlay.

The following table provides information about whether Configuration Manager supports an opportunistic persist and a forced persist to manage write filters. None of these features require or support write filter exceptions. Set the value to 4 to disable System Restore or 0 to enable System Restore. Double-click Start , and set the value to 4 to stop the service from starting or to 0 for normal startup.

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