What should I use for legacy file server migration?

It depends on what you’re migrating from, to, and what constraints you have, but for most legacy file server migrations the usual choices are:

Common tools/options

• Robocopy (Windows-to-Windows)
  • Best for copying large file shares with permissions, timestamps, and retries.
  • Common for SMB share migrations.
• Storage Migration Service (SMS) in Windows Server
  • Good if you’re moving from older Windows file servers to newer Windows Server versions.
  • Can migrate data, shares, and local users/groups.
• Azure File Sync / Azure Migrate
  • If the target is Azure or a hybrid setup.
• rsync (Linux/Unix-to-Linux/Unix or mixed environments)
  • Best for preserving metadata in Unix-like environments.
• DFS Namespace + DFS Replication
  • Useful for transition/migration with minimal downtime, especially if you need a phased cutover.
• Vendor tools
  • For NAS appliances like NetApp, Dell EMC, QNAP, Synology, etc., vendor migration tools often preserve ACLs and share settings better than generic copy tools.

If you want the safest default recommendation

• Windows legacy file server → new Windows file server:
  Storage Migration Service if available, otherwise Robocopy
• Linux/Unix file server migration:
  rsync
• Heterogeneous or NAS migration:
  Vendor migration tool or a staged copy + validation + cutover approach

What matters most when choosing

• Preserve NTFS/ACL permissions
• Preserve timestamps/ownership/auditing
• Minimize downtime
• Handle long paths, open files, and large file counts
• Ability to do a delta sync before cutover
• Reporting and validation

If you tell me:

1. source OS/platform,
2. target platform,
3. data size, and
4. whether you need to preserve permissions/ACLs,

I can recommend the best tool and migration approach more precisely.