Deploy an OS by Using SMS

Task 3: Upgrading an Existing OS
Installing the OS on a fresh system is one thing, but how can you use the OSD to upgrade an existing OS? When upgrading an OS, the main challenge is to install the OS while maintaining the user and computer states. The OSD addresses this challenge by using phases, which let you define or perform custom actions.

When you upgrade an OS on a system, the OSD captures the user's state (i.e., user profiles and documents from the original OS), then restores this information after the new OS is deployed. To perform these user-state actions, the OSD uses User State Migration Tool (USMT) 2.6, which is integrated with the OSD, although you need to download and install USMT 2.6 separately. (You can download USMT 2.6 via a link on the SMS 2003 OSD Feature Pack Web site.) USMT 2.6 captures all profiles on the existing OS and not just the currently logged-on profile. If you don't want to use USMT, you can run another application or script to capture and restore the state.

By default, the OSD saves the user-state information to the local disk in a subfolder of C:\minint. (The minint directory stores other data besides the state data; furthermore, it's the only directory that isn't deleted when the OSD cleans the disk to prepare for the new OS extraction.) You can save the user state to a Universal Naming Convention (UNC) path if you want (which you'd have to do in machine-refresh scenarios—that is, when a user gets a new machine). However, the best practice is to store the state data on the local disk; doing so is much faster than saving and restoring the potentially large state data to a share on the network.

The process of deploying the OS upgrade is the same as delivering any other application via SMS. SMS creates an advertisement and assigns the OS installation program to a collection. (The collection computers must be running the SMS 2003 Advanced Client SP1 to be able to recognize OS programs.) Typically, via SMS you'd offer the new OS to the collection perhaps two weeks before the mandatory install date, so that users can install the OS when it's convenient for them, but enable a data and time for an automatic installation for clients that haven't had the OS installed. In this situation, because SMS contains complete software and hardware inventory data for all the machines you want to target, you can customize the upgrade—for example, upgrade only Windows 2000 systems that are at least Pentium 3 machines with 128MB memory and 10GB C drive partitions. The OS advertisement appears to end users just like any other advertisement; they're prompted that a new program is available and can install it via the standard Add or Remove Programs Control Panel applet.

After the advertisement has run, the SMS OS program executes and displays a countdown screen (you can configure the countdown time value, which is 30 minutes by default), which lets the user install the OS now or postpone the installation. When the user chooses to install the OS, the machine state is captured to the configured location (either C:\minint or a UNC path as described earlier), then the OSD WinPE is installed in C:\minint. OSD replaces the root active partition files ntdetect.com and ntldr with versions that use the C:\minint location instead of the standard Windows installation (the original versions are backed up in C:\minint\backup). The machine then reboots into the now-local OSD WinPE, deletes all files on the disk except those in the minint folder, and downloads the new OS. This is the same process that the OSD uses for a brand-new OS deployment, and you can use the same OS image for both new-install and upgrade scenarios. The only mandatory difference between a new OS install and an upgrade is that a state-restore phase runs after the mini-setup wizard finishes to restore the state data from the minint or UNC location.

A More Powerful SMS 2003
The OSD expands SMS 2003's capabilities to let you create and install OS images on computers across your organization. The OSD uses existing Windows technologies that you're probably familiar with, such as Sysprep and USMT, and also gives you an opportunity to adopt Microsoft's latest imaging format, WIM, which will be the basis for OS imaging in the next generation of Windows. Most importantly, the OSD lets you install new OSs as well upgrade existing OS versions through the SMS 2003 application-deployment infrastructure.