Backup NextCloud server

Used rsync to backup my personal files on my NextCloud server. However it appears it just backed up everything again, because the file all timestamps were today. For as long as I have been using Linux, I should know how to use rsync better,. Did some research and think I found solution…maybe

rsync –update -raz –progress ‘/home/myfiles…/’ ‘/media/sdb1/’.

However it just ended (return to prompt), with no final summary that I’ve seen before?