rsync (Everyone seems to like -z, but it is much slower for me)
- a: archive mode - rescursive, preserves owner, preserves permissions, preserves modification times, preserves group, copies symlinks as symlinks, preserves device files.
- H: preserves hard-links
- A: preserves ACLs
- X: preserves extended attributes
- x: don't cross file-system boundaries
- v: increase verbosity
- --numeric-ds: don't map uid/gid values by user/group name
- --delete: delete extraneous files from dest dirs (differential clean-up during sync)
- --progress: show progress during transfer
ssh
- T: turn off pseudo-tty to decrease cpu load on destination.
- c arcfour: use the weakest but fastest SSH encryption. Must specify "Ciphers arcfour" in sshd_config on destination.
- o Compression=no: Turn off SSH compression.
- x: turn off X forwarding if it is on by default.
Original
rsync -aHAXxv --numeric-ids --delete --progress -e "ssh -T -c arcfour -o Compression=no -x" user@<source>:<source_dir> <dest_dir>Flip
rsync -aHAXxv --numeric-ids --delete --progress -e "ssh -T -c arcfour -o Compression=no -x" [source_dir] [dest_host:/dest_dir]
To not let this stand as is, some facts: compression is off by default in ssh (and always has been in openssh), tty allocation is off when used in rsync and x forwarding does not affect bulk bandwidth in any way. Any difference in speed measured is not due to these options, but more likely because of a bad test setup, such as first making tests with cold disk cache and the with hot cache. The only change that can affect speed is the cipher (and not turning compression explicitly on in rsync or ssh).