The Update Manager displays system managed baselines that are generated by vSAN. These baselines appear by default when you use vSAN clusters with ESXi hosts of version 6.0 Update 2 and later in your vSphere inventory. If your vSphere environment does not contain any vSAN clusters, no system managed baselines are created.
The system managed baselines automatically update their content periodically, which requires Update Manager to have constant access to the Internet. The vSAN system baselines are typically refreshed every 24 hours.
You use system managed baselines to upgrade your vSAN clusters to recommended critical patches, drivers, updates or the latest supported ESXi host version for vSAN.
System managed baselines cannot be edited or deleted. You do not attach system managed baselines to inventory objects in your vSphere environment. You can create a baseline group of multiple system managed baselines, but you cannot add any other type of basline to that group. Similarly, you cannot add a system managed baseline to a baseline group that contains upgrade, patch, and extension baselines.