Architecting VMware vSAN 6.2 : vSAN Technology and Features Overview : 3.2 vSAN Key Features : 3.2.5 Snapshots and Clones
   
3.2.5 Snapshots and Clones
vSAN 6.0 introduced a highly efficient VM-centric snapshot and clone mechanism with support for up to 32 snapshots per clones per VM and 16K snapshots per clones per cluster. The new snapshot and clones offer performance improvements over the previous versions. For more information about snapshots in vSAN 6.0 and later, see the following two papers:
vsanSparse – Tech Note for Virtual SAN 6.0 Snapshots
https://www.vmware.com/files/pdf/products/vsan/Tech-Notes-Virtual-San6-Snapshots.pdf
VMware Virtual SAN Snapshots in VMware vSphere 6.0
https://www.vmware.com/files/pdf/techpaper/vsan-snapshots-vsphere6-perf.pdf