On 2006/03/22 14:15, Marco Fretz wrote: > may you explain me the thing with the delta compression?
rsync, rdiff-backup and some other programs use an algorithm which sends only the differences between files. this is called delta compression. 'delta' refers to the change in value, it's mathematical notation: http://en.wikipedia.org/wiki/Delta_(letter) This is different to what's normally called 'incremental backup' where you determine which files are updated or new since the last backup, and store a complete copy of them. > i want to backup some files incremental over ssh with tar. is that > possible? Yes. You can use find(1) to select files changed since the last run have tar(1) add just those files, outputted to stdout, and pipe it over an ssh session. This way avoids temporary files on the machine you're backing up, but if you have large files with small changes it's not bandwidth-efficient. $ find /some.dir -newer /tmp/last.backup | tar czf - -I - | ssh some.host "cat > /tmp/backup.tar.gz" && touch /tmp/last.backup You can have tar(1) create one big uncompressed temporary archive on the machine being backed up, and rsync it across (by default, this uses ssh). This obviously uses a lot of space for a temporary file, but possibly saves bandwidth over the first method. Or you can use a tool designed for the job, something like rsync or diff-backup, and not worry about tar files at all. about tar files at all. > and is it possible to sudo the tar process on the remote machine? Yes, of course it is, just be careful how you set everything up so you don't give full root access without a password.
