I never heard of WORM backups, but it sounds interesting. You gave me something to dig into.

Just FYI, mirrored backups are great as a solution to complete failure, but… File corruption or just accidental deletion can mean you don’t notice files are just straight up missing.

This is the same problem with cloud storage, but there are solutions like rsync and only backing up the differences that can alert you to large volumes of file changes during the backup.