is there a way to silently rollback installation upon failure of new update (using installaware or independent of installaware). I want the installer to run and only if everything is installed correctly (and running properly if possible) is the old version removed.
InstallAware and other tools such as Window Installer XML and InstallShield author Window Installer databases. Windows Installer handles this automatically for you by providing built in transactional installation and upgrade capabilities. The behavior you are looking for is controlled by where you choose to schedule the RemoveExisitingProducts action. See:
•Between the InstallExecute action, or the InstallExecuteAgain action, and the InstallFinalize action. Generally the last three actions are scheduled right after one another: InstallExecute, RemoveExistingProducts, and InstallFinalize. In this case the updated files are installed first and then the old files are removed. However, if the removal of the old application fails, then the installer rolls back both the removal of the old application and the install of the new application