rsync is apparently extremely inefficient in a number of common cases, such as simply renaming a folder (completing synchronizing all the files in the folder ag

rsync is apparently extremely inefficient in a number of common cases, such as simply renaming a folder (completing synchronizing all the files in the folder again). Also, some IMAP servers store message flags in the filename (when using Maildir). This means that a message that goes from unread to read, it would appear to rsync that one file was deleted and another created (as the filename on disk has changed); the "newly created" file (which could be many MBs in size, depending on its contents/attachments) would then have to be completely synchronized again. I didn't realize just how inefficient it was until a few days ago when I read an article [0] comparing rsync against ZFS replication (even if you're not familiar with ZFS, you'll understand). [0]: http://arstechnica.com/information-technology/2015/12/rsync-net-zfs-replication-to-the-cloud-is-finally-here-and-its-fast/ http://arstechnica.com/information-technology/2015/12/rsync-...