Installation of an operating system update on a data processing system can begin by receiving one or more packages containing an operating system (OS) update that includes a first portion of the OS update and a second portion of the OS update. The first portion, once installed, provides a bootable OS which allows other applications to execute on the OS even without the second portion being installed. After the first portion has been installed, the installation process (e.g., an installer) commits the data processing system to boot off the first portion. After committing to boot off the first portion, the data processing system cannot boot off the prior OS. After the committing, the data processing system attempts installation of the second portion, and this attempt occurs automatically in response to successful installation of the first portion.