Advantech TPC-300 Series, User Manual

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23 TPC-300 Series/TPC-B510 User Manual
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Figure 3.2 Enabling UWF - Step 2
3.3 UWF Overlay
UWF protects the contents of a volume by redirecting all write operations on that vol -
ume to the overlay, which is a virtual representation of the changes to the volume.
Conceptually, an overlay is similar to a transparency overlay on an overhead projec -
tor. Any change that is made to the transparency overlay affects the projected picture
as it is seen by the viewer. However, if the transparency overlay is removed, the
underlying picture remains unchanged.
UWF can store the overlay either entirely on RAM (RAM-based) or in a pre-allocated
file on the system volume (disk-based). Advantech provides a utility for configuring a
UWF overlay. Refer to the steps below to enable this function.

Note
UWF function must be disabled in order to configure a UWF overlay. After the
configuration is complete, UWF function can be enabled again.