XenServer supports 3 different types of storage repositories (SR)
1) File based vhd, which is a local ext3, remote NFS or SMB filesystems, which supports thin provisioning for vhd
2) Block device-based vhd format (SAN based on FC, iSCSI, SAS) , which has no support for thin provisioning of the virtual disk but supports thin provisioning for snapshots
3) LUN based raw format - a full LUN is mapped as virtual disk image (VDI) so to is only applicable if the storage array HW supports that functionality
SMB storage (CIFS) is supported for XenServer 7.x Enterprise Edition