You do not have a real backup until you have a verified backup.
That means all the data can be read (a physical check on the storage medium) and is cryptographicallly proven to be intact/unchanged with no files or folders missing.
No photographer or videographer or other professional should be operating without data integrity validation. Whether bit rot or malware or software bugs or hardware problems, can you afford to remain unaware of data corruption, or to not know with provable certainty whether your backups (and originals!) are intact and undamaged?
Or keep guessing about whether your backups suck.
Cross platform: IntegrityChecker Java (icj) supports Mac, Windows, Linux, etc—anything with Java, an unrivalled cross-platform data integrity solution.
How to update and verify files — drag and drop
icj update finds all new and changed files that need hashing and updates the hashes for all.
icj verify reports new files, deleted files, changed files, corrupted files (if any).