Since Machine Creation Services (MCS) was first released in XenDesktop 5.0, every VM created has used a delta structure for the VM`s created on a hypervisor. This means that all VM writes go to the delta disk, but the base disk is shared across all VM disk reads go the shared base disk …
Quelle: XenApp and XenDesktop 7.11 MCS Full Clone Support | Citrix Blogs