The Enhanced Write Filter (EWF) component provides an upper filter in the storage device driver stack that redirects disk write operations to volatile (RAM) or non-volatile (disk) storage. The EWF has been enhanced in the following ways:
- The configurable options have been modified to make them more intuitive and robust
- An option to disable Background Disk Defragmentation has been added. By default we are disabling this feature for your device to reduce the disk write activity. This saves wear on the flash and saves overlay space.
- RAM (Reg) has been added as an Overlay Type option
For more information about EWF, see the EWF Overview topic in Windows XP Embedded Help.
Services
There are no services associated with this component.
Associated Components
This component is associated with the EWF Manager Console application component, with the EWF NTLDR component, and with the Enhanced Write Filter API (EWF API) component.
Settings
This component provides a number of configuration settings for each EWF volume. These settings are specified in Target Designer, on the EWF Configuration Settings tab. After you specify the number of protected volumes, you can use the Previous Volume and Next Volume buttons on the EWF Configuration Settings tab to iterate through the protected volumes and configure them.
The following table shows the settings that are used to specify the EWF volume configuration.
| Setting | Description |
|---|
| Number of Protected Volumes | Sets the number of volumes EWF will protect. Range: 1-9 |
| Maximum Number of Overlay Levels | Sets the maximum overlay level for DISK overlays. Range: 1-9. (Always 1 for RAM overlays.) |
| EWF Partition Size in KBytes | Sets the size of the EWF partition. Defaults to 1024 for DISK overlays, value is N/A for RAM overlays. |
| Disable Background Disk Defragmentation | Yes/no checkbox |
| Enable HORM | Yes/no checkbox |
The following table shows the configuration settings for each specified protected volume.
| Setting | Description |
|---|
| Protected Volume Prev/Next Buttons | Moves to individual settings for each protected volume (governed by # volumes option above) |
| Start EWF Enabled | Yes/no checkbox (per volume) |
| Enable Lazy Write | Yes/no checkbox (per volume – enables "Lazy write" mode) |
| Disk Number | Specifies disk(x) value in arc path for this volume |
| Partition Number | Specifies partition(x) value in arc path for this volume |
| Overlay Type | Select between DISK, RAM and RAM (Reg) modes for this volume |
| Optimization Option | Select options to optimize EWF performance |
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