To protect this space from undesired writings and to avoid not necessary flash memory activities, Windows Embedded use a write filter. The filter diverts I/O requests, coming from processes, to temporary savings into the RAM memory. Data temporary stored on RAM memory are accessible to users as long as the thin client is powered on. This explains why when a thin client reboots, it starts from the previously saved configuration and no savings were made in the flash memory during the running phase of the thin client.
The write filter is also a benefit that helps to extend the life of the flash memory.
To allows permanently writings onto the flash memory the write filter has to be disabled before writings are made.
Tip for software installation
When you are installing new software on the thin client be sure to disable the write filter before the installation of the new software. Remember that changing the write filter status needs a device reboot.
Tip for maintaining a clean installation
Whether you plan to install new software or modify the file system on the thin client be sure to do that in fresh rebooted thin client. In this way you will start the writings from a "clean" installation of the thin client and only the necessary writings on the DoM will be executed and saved. After the configuration changing (or new software installation) enable the write filter again (this will reboot the thin client) to protect the DoM from undesired writings.
ΒΆ Unified Write Filter (UWF)
The Unified Write Filter (UWF) protects the flash memory from changes.
UWF is enabled by default on Praim Windows Embedded thin client. When it is disabled the flash memory can be written without protection.
To modify UWF configuration please access the Praim Manager (see Accessing the Praim Manager and then click on the "UWF Manager" icon.
The buttons allows to:
- Disable/Enable: it toggles the "After restart" status (Enabled/Disabled). The "After restart" status indicates the status of the write filter that will be available after the thin client reboot. You have to use this function to enable or disable the write filter and then reboot the thin client to make it effective. "Currently" indicates the current status of the write filter.
- Refresh: will refresh the information on memory occupation. "Consumption" reports how much memory is currently used by the write filter. "Available" reports how much memory is currently available to the write filter.