VMFS6 file system was in vSphere 6.5. Of the many new features introduced with VMFS6, one of the notable features is Automatic Space Reclamation.
Automatic space reclamation, also sometimes referred to as UNMAP is a feature that allows the hypervisor (vmkernel) to reclaim space when files (data) are (is) deleted from a virtual machine with a thin provisioned disk. The following video from VMware Tech Pubs provides an ease way to understand the same.
Here is an excellent playlist of videos from VMware Tech Pubs. The video list features some of the new features introduced with vSphere 6.5. If you plan to take the VCP 6.5 exam this is something that you should definitely watch.
Here’s another very nice video from VMworld TV (VSP2122), which talks about vMotion. Highly recommended for vSphere administrators.
VMworld TV, has recently posted a great video on Understanding Memory Performance Management. Highly recommended anyone working in a vSphere environment and especially useful when designing one.