A thin clone is a writeable copy of a volume, which shares the same data blocks as the parent volume. This allows the administrator to provide a copy of the production database volume to the test environment without affecting the production data. It also allows to test the data without affecting the production data, and also it doesn't require additional storage space.

When a Windows client uses the SMB protocol to access a multiprotocol file system from a Dell Unity XT NAS server, the SID (Security Identifier) of the Windows user is mapped to a UID (User Identifier) on the UNIX file system. If no mapping is found in the local group database, the domain controller is checked to see if the SID is present there.
The domain controller can provide the information needed to map the SID to the corresponding UID on the file system, allowing the Windows user to access the files. If the SID is not present in the domain controller, the Windows user's access would be removed.