Which tool can be used to migrate file data for Windows hosts from a legacy VNX array to a new Dell Unity XT array?

Robocopy (Robust File Copy) is the correct tool for this scenario. It is a native Windows command-line utility specifically designed for migrating file data between servers. When migrating file data for Windows hosts from a VNX NAS to a Dell Unity XT file system, Robocopy is the recommended host-based tool because it can reliably copy files, directories, and crucially, preserve the associated NTFS permissions (ACLs), timestamps, and other file attributes. This ensures a seamless transition for end-users with no loss of access rights or metadata.

A. SANCopy: This is a block-level data mobility tool used for migrating LUNs, not for file-level data migrations from a NAS or file share.
B. Rsync: This is a utility native to Linux/Unix environments. While versions exist for Windows, it is not the standard tool and may not preserve Windows-specific NTFS ACLs as reliably as Robocopy.

1. Dell Technologies White Paper (H15163.5): Dell Unity: Migration from VNX. In the "Host-based file migration" section, the document states, "For Windows clients, a utility such as Microsoft Robocopy can be used to copy the data from the source to the destination." (Page 23)

2. Dell Technologies White Paper (H15162.4): Dell Unity: Migration Technologies A Detailed Review. The section "Host-Based Migration" discusses using host-based tools for file migration. It mentions, "For file migration, common tools such as Robocopy for Windows... can be used to copy data from a source system to a Dell Unity system." (Page 18)

3. Microsoft Docs: Robocopy. The official documentation describes Robocopy as a tool to "copy file data from one location to another" and lists parameters like /copyall or /sec which are used to copy NTFS access control lists (ACLs), ensuring permissions are migrated correctly. (Reference: robocopy /? command-line help and associated online documentation).