I wanted to do a multi-part blog from a high level on how servicing in Windows works. The majority of this will apply to Vista, Win7, 2008 and 2008R2, however there are some things that happen in Win7/R2 that do not happen in Vista/2008. When appropriate, I'll try to call those out.
So first, a few of the basics. What is servicing? Servicing is the act of installing a role, feature, service pack or windows update against a Windows OS. Most of the time servicing is done in an online state. In this case, online means that the operating system is up and running when a change is made. Online servicing is what most people do and is usually done via Windows Update or double clicking a downloaded update. There is also an offline state. Offline, of course, means that the installation is happening against a non-running version of Windows. This is what a lot of larger corporations and OEMs do with their image files, they mount them with IMAGEX or DISM and then install hotfixes or other updates against those images to reduce their patch time when the image is rolled into production. The reason this distinction is important is because certain operations cannot be done offline. Namely, service pack installations. It's a request we get all the time and it cannot be done. There are several reasons for this but I wont go into them here, just take it from me, you cant do it :)
Now that we have OS state out of the way, let's talk a little bit about the various servicing components and what they're actually there for:
So, those are the three big moving parts. I'll break them down more as this series progresses, but I wanted to start with this. We'll look at whats held in each of these parts over the next couple of weeks and then walkthrough a package installation.