Windows Imaging Format (WIM)
Been getting quite a few questions about this lately and thought I’d share just a little bit about what I love about this new imaging format. Basically the WIM format was introduced in Windows Vista and unlike its competing technology the "Ghost", WIM is a file-based image format as oppose to the sector-based imaging technology. Because of this, the WIM introduces many interesting benefits. The ones I like best are:-
Hardware agnostic – this means that only one image to address many hardware configurations
Multiple images in one file – and I’ve been telling people about this especially if you’re doing OSD. A single WIM file can contain the many standard corporate images that you may have. Then when deploying, you select the image that you want to get installed on to the client machines.
Compression – and I love this the best. A typical installation of an example, Windows XP Pro would typically take up about 1.2GB of disk space. Guess how much a compressed WIM would be? I normally get about ~250MB after the image is captured. This is really because of the use of a single instance. What this means is that it stores two or more copies of the same file for the space of just one copy. For example, if images 1, 2, and 3 all contain file A, single-instancing stores a single copy of the file A and points images 1, 2, and 3 to that copy.
Offline updating – which gives the ability to update, modify, add, remove or append to components of the image without creating a whole new image again. What one would probably do is to boot up the image, make the necessary changes or patches and then create the new image. WIM allows you to do all this offline.
Installs on partitions of any size – because it is not a sector-based imaging technology, it does not matter whether or not the image and the destination partition are of the same size.
Non-destructive – would mean that you can now leave data on the volume to which you apply the image to because by applying the image, it does not remove any of the disk’s content.
Going into more details of the WIM technology can be daunting, so to explain in more details, a white paper is available that is applicable for developers that can be found on the link below:-