PRESERVING USER CHANGES TO A SHARED LAYERED RESOURCE

User changes may be preserved across updates to a layer. When a layering client mounts a layer, a corresponding layering write cache is mounted. Changes to layered resources, such as files, registry entries, and registry values, are made only to the layering write cache. A request to create a file in the layer is directed to the layering write cache such that the new file is created in the layering write cache. A request to open a layered resource, is directed to the layered resource if the layered resource is in the layering write cache. A request to write to a layered resource is directed to the layering write cache if the layered resource is in the layering write cache. If the layered resource is not in the layering write cache, the layered resource is copied to the layering write cache before redirecting the write request.