For many years now, I've been using the old Unix utility rsync to backup my computer to an external hard drive. As outlined in two earlier posts (here and here), it has always seemed to work quite well for me... until recently. After replacing a failed hard disk and restoring my /home filesystem, I noticed that one of my two backup drives contained many more files than did the other one. After inspecting these files, it appeared that most of the extra files should, indeed, have been deleted many months ago. I've always given the "--delete" option to rsync, and it's appeared to work, so why did these files not get removed?