This weekend I'm planning to do an upgrade going from a 2009 Mac mini server (was Snow Leopard Server, then upgraded to Mountain Lion and then to Mavericks) with a bunch of external drives (12TB total) to a new, 2012 i7 Mac mini, 10GB RAM and the drive partitioned into two 500GB partitions to match the drives in the 2009. The servers run headless. I run the following services: File Sharing, Caching, TimeMachine, DNS, DHCP, VPN, Contacts and Calendar, Plex, iTunes and iPhoto to manage music and photo databases accessed by Plex, and a Parallels Windows virtual machine for Quicken. I think that's all. The problem is how to approach this, so I'm asking for input from anyone who has attempted it. I'm considering the following approaches: Clone the server internal drives into the new server, move over the externals. Then upgrade the new server to Yosemite and Server 4. Looks like the fastest approach but the system cruft will just increase. Put Yosemite and Server 4 on the new mini and configure it from scratch. Lots of work but should be cruft free. Follow the Apple recommended procedure -- install just Yosemite, use Migration Assistant with old server in target disk mode, install Server 4, pray. Something else (maybe use the new mini as a desktop computer because the "upgrade" is a disaster waiting to happen).