Why this matters
File migrations look like a copy job. They are not. The hard part is not moving the bytes; the hard part is preserving the permission tree (who could see what), the shared-link history (every external link your customers and partners have already bookmarked), the version history (the audit trail that compliance depends on), and the folder semantics (the folder names your team has built workflow around for years). Done badly, you destroy the institutional knowledge encoded in the file system. Done well, the move is invisible.