I had this question a number of times now. Those of you familiar with VSAN will know that if a component goes absent for a period of 60 minutes (default) then VSAN will begin rebuilding a new copy of the component elsewhere in the cluster (if resources allow it). The question then is, if the missing/absent/failed component recovers and becomes visible to VSAN once again, what happens? Will we throw away the component that was just created, or will we throw away the original component that recovered?
As part of a quick reference proof-of-concept/evaluation guide that I have been working on, it has become very clear that one of the areas that causes the most confusion is what happens when a storage device is either manually removed from a host participating in the Virtual SAN cluster or the device suffers a failure. These are not the same thing from a Virtual SAN perspective. To explain the different behaviour, it is important to understand that Virtual SAN has 2 types of failure states for components: ABSENT and DEGRADED.