Why does this rsync command not delete files in destination directory

Question

rsync -av --del ~/ /media/m/USB\ Stick/kopia/rsynclinux/

For reasons unknown I was living in a false impression that once I remove a file from home directory in source the file would be removed in destination as well.

I had to reinstall and restore the backup... only to find how wrong I was. I now have an incredible mess of obsolete & duplicated files!!

Well I won't travel back to the past to make a proper backup, instead I'm stuck with slowly, ardously bringing order to my old notes.

But at least I want to avoid such mistakes in the future. Why does this call to rsync fail to delete files?

Note I read this: rsync doesn't delete files in destination directory But as U can see my call to rsync does not include a wildcard so the two problems are not the same

Answer 1

The --del option is an alias for --delete-during. The option you were looking for is --delete.

There's a good summary of the different options at https://superuser.com/questions/156664/what-are-the-differences-between-the-rsync-delete-options.

Answer 2

If /media/m/USB\ Stick/kopia/rsynclinux/ is a FAT-based or NTFS filesystem it cannot store all the attributes (metadata) for files copied from a native-Linux filesystem. This will trigger rsync into considering there has been an error copying the files, and the --delete will be disabled.

From the documentation, man rsync, under --delete (implied by --del or --delete-during):

If the sending side detects any I/O errors, then the deletion of any files at the destination will be automatically disabled.