Actually this was a good idea, but it takes a millennia to start to copy actually something.
rsync -avr --delete /Volumes/Toshiba/iPhoto\ Library/ /Volumes/LACIE/iPhoto\ Library/
Then I had to copy two backups and was fed up about the rsync never actually to start copying for hours.
I found this article
http://blog.brettalton.com/2013/08/05/how-to-speed-up-rsync-on-your-mac-and-stop-the-dreaded-building-file-list/
and installed homebrew and then the new rsync and am using the following command now:
rsync -a --info=progress2 /Volumes/WD_2TB/ /Volumes/Toshiba/
Now there is some action, but disappointingly it crawls and I don't know why. Is it because there are gazillions of small files or is something else broken?
Let's wait and see.
Don't know but I feel more comfortable with this command as it actually does go ahead for now (still don't understand enough about the processing):
rsync -aP /Volumes/WD_2TB/ /Volumes/Toshiba/
and this with rsync 3.1.1
