A server is restored by creating an image of a local drive of a server; replacing a driver in the boot up procedure of the server, the replacement driver redirecting disk drive access requests from the local drive to the image; on-demand copying portions of the operating system needed for start up from the image to memory of the server; and copying a remainder of the image from the image to the local drive as a background process. The data is copied on-demand from the image to the local drive. The copying is performed over a network. The image is created on a different server connected to a network. The copying of the remainder of the image, after critical start-up data has been copied, is done based on a priority of a sector of the image being copied. A bitmap is created corresponding to sectors of the image, and the server decides whether to access a particular sector on the local drive or on the image based on the bitmap.