Maintenance Windows

Let's talk about maintenance windows in SCCM, a new feature for software distribution and software updates.  Maintenance windows usually make sense in a server-based scenario where servers have defined service windows where they can be taken down for changes, including software updates.  You can define a maintenance window for a collection by choosing "Modify Collection Settings" and then going to the Maintenance Windows tab.

The window uses an estimated time to execute the entire install.  This time is comprised of the following settings:

1. Restart countdown time (Restart countdown time has a default of 5 min and is available to change on each collection in the Admin UI). 

2. System restart turnaround time (Site Control File-only setting, which has a default of 10 min).

3. Maximum Run Time, which is the per-update installation time and has a Site Control File-only default setting of 20 min for Updates and 60 min for Service Packs.  However, the difference from below is that this setting can be changed in the Admin UI for each update.  This setting for each update can be found in a list view when looking at updates in the update repository node, update list node, or in a search folder

If more than 1 update is needed to be installed, say Update 1 with Max Run Time (MRT) of 20 min, Update 2 with MRT of 5 min, and Update 3 with MRT of 30 min, we will start by installing the update with the smallest MRT, in this case Update 2.  We watch the installation & if Update 2 finishes, we look for the next shortest MRT and see if that will fit in the window, and so on, until we run out of available time.

In the the situation when the only thing left to do is a pending reboot when waiting for a Maintenance Window, we will only use the restart countdown time and the system restart turnaround time and not use the MRT.