I have setup rsnapshot with a cron job and stored 7 daily backups of my online server to a backup storage. Everything seemed to went fine since I could access everything in my backups I mounted via NFS.
One day I actually needed to restore a lost important file from my backup. Unfortunately each daily backup just showed me the content of the live system. Every change I made on the live server was instantly done in any backup as well.
It seemed like there was no real backup, but only alternative link structures pointing to the same live-system. This for sure wasn't what I needed.