Transfer files from one server to another using rsync

I needed to transfer 10.000 images from one server to another, so I used rsync for this task:

rsync -ahuzP --stats -e "ssh -p 4721" "/var/www/img" root@example.com:/var/www/

This will copy the folder /var/www/images and all of its contents from the local server to the remote server example.com. The folder /images will be created in the target’s /var/www/ directory. I specified a non-standard SSH port using the -e parameter and root as user. I also used the following rsync parameters:

-a, --archive               archive mode; equals -rlptgoD (no -H,-A,-X)
-v, --verbose               provide more information during transfer
-h, --human-readable        output numbers in a human-readable format
-u, --update                skip files that are newer on the receiver
-z, --compress              compress file data during the transfer
-P                          same as --partial --progress
--stats                     give some file-transfer stats

See http://explainshell.com for a full explanation of what the command does.