I created a vSAN policy using H5 client and specified "Site disaster tolerance None - Stretched Cluster" and "Failures to tolerate 1 failure - RAID-1 (Mirroring)" as per understanding all components of all object must be created on a single site (FD) but when I tested the policy find mostly it's true but it even sometimes create components in multiple sites (Screenshot attached). VM Home object's components are created in different site with a witness on each site.
Any help to understand the policy will be a great help. Thanks
You need to specify the locality as well, if you don't specify the locality then components may be places across fault domains. I discussed this in the following blog post: http://www.yellow-bricks.com/2019/05/28/site-locality-in-a-vsan-stretched-cluster/