I just got the message "Time Machine completed a verification of your backups on MacMini. To improve reliability, Time Machine must create a new backup for you." on my rMBP connected to my mini server. I tried the fixes listed on so sights but just read on the excellent site http://pondini.org/TM/Home.html, that it is pretty much gone. Now that I need to start over I am questing the whole running time machine from OS X server thing. I wondering on our two MacBooks that are the server clients if I am better off just connecting the time machine disk vis usb when we plug the in to charge. Has anyone found Time Machine to be unreliable when running OS X server? I have the latest updates and versions.