@Nihils Yes, defaults matter (ext4 now more than ext3). RHEL defaults to xfs, for some reason (and since it has worked at $DAYJOB, we kept xfs after switching to Ubuntu, even if the installer touts ext4).
Back to my failing harddisks, I have now realized that doing backups with rsync --delete isn't that good when the source is a slowly degrading file system. Seems I lost some digital photos from 10+ years ago.