@lElOUCHE_79, Objects (e.g. .vmdk, .vswp, namespaces) stored on vsanDatastore with default FTT=1, RAID1 policy are basically stored as two complete copies (e.g. so that one can be unavailable but the data still accessible from the other replica).
Sorry but I am unsure what you mean regarding source etc. - are you referring to what happens when migrating objects to vsanDatastore?
This article outlines the basic concepts well:
https://core.vmware.com/blog/vsan-objects-and-components-revisited
