Rsync and making sure all files have been transferred before applying the changes

Question

I was wondering if there is a way to tell rsync to only apply changes (delete, overwrite, create) only if all files in the file list transferred successfully.

Just to clarify, this would essentially be putting a transaction around the transfer.

Answer 1

you could use a filesystem (btrfs, zfs) with snapshot-features:

• snapshot your current state
• rsync
• check exit code of rsync and rollback if needed

you can also enroll your own snapshots:

• make a copy of the files (this becomes the working area)
• rsync to the working area
• check exit code of rsync and move working area over the original files if exit code was ok.

Answer 2

You could use the --delay-updates option, or if you want really atomic updates, the atomic-rsync script (included in Debian as /usr/share/doc/rsync/scripts/atomic-rsync.gz).

Answer 3

From the 'rsync' man pages, you may be in luck only for deletes:

Some options require rsync to know the full file list, so these options disable the incremental recursion mode. These include: --delete-before, --delete-after, --prune-empty-dirs, and --delay-updates. Because of this, the default delete mode when you specify --delete is now --delete-during when both ends of the connection are at least 3.0.0 (use --del or --delete-during to request this improved deletion mode explicitly). See also the --delete-delay option that is a better choice than using --delete-after.