Fault tolerance and storage policies
RAID-1 (Mirroring) FTT-1 is the default storage policy, while thin provisioning is the object space reservation setting. The cluster will continue using this default storage policy unless it is changed, or a new policy is applied.
Important note
You could see a VM storage policy named vSAN Default Storage Policy with Object Space Reservation set to thick provisioning when you log in to the vSphere Client. Please note that the cluster does not use this as its default storage policy. This rule is still in effect for historical reasons, although thin provisioning will soon replace it.
The Microsoft vSAN Management Storage Policy is used by all of the software-defined data center (SDDC) management VMs (vCenter, NSX manager, NSX controller, NSX edges, and others), with Object Space Reservation set to thick provisioning.
