A “thin client” (sometimes also called a lean client) is a computer device that depends primarily on a central server for processing activities, and mainly focuses on conveying input and output between the user and the remote server. This is to be contrasted with a “thick” or “fat” client, which does as much processing as possible on the local device, and passes only data for communications and storage to the server. Many thin client devices run only web browsers or remote desktop software, meaning that all significant processing occurs on the server.
Thin client computers typically have a very small flash storage device that contains the operating system (OS) and all of the software used on that particular computer. The thin client operating system plus all of the added software is called a “flash image” or “operating system image” and can be handled as one large file.
It can be desirable to update a thin client operating system from time to time. For example, a user of a network having multiple thin clients may desire to modify the original flash image or create their own flash image and redeploy this new image to all of the associated thin clients. Some thin client operating system images provide a feature to re-image the thin client with a new version of the flash image. However, thin clients typically do not have enough available memory to allow downloading of the entire flash image in one operation. Consequently, multiple write cycles are used. Unfortunately, if the thin client device loses power or network connectivity during the relatively long write cycles for downloading the new flash image, it is possible to corrupt the image of a thin client so that the device will not boot at all.