I have a server running Server.app (3.2.2) on Mac OS X 10.9.5. It hosts File Sharing, Mail, VPN, Websites, DHCP, DNS, and Open Directory etc. It also hosts phpBB3 bulletin boards.
Because the OX version is not up-to-date, I want to transfer everything to a new Mac mini running OS X El Capitan (10.11). I thought it would be safer to use another machine than simply updating the running server machine itself.
The server machine has two partitions and one is used for the Time Machine backup.
I thought a situation like this is not uncommon, and should be straightforward. But seemingly I was wrong... it might be more like heart bypass surgery.
My initial plan was to import the latest Time Machine backup of the old server to the new Mac mini with Migration Assistant.app. While both machines are connected to the same local network, I could not let Migration Assistant.app find the backup file. I chose "From a Mac, Time Machine backup, or startup disk" on the screen, but on the next screen the old server is not automatically shown, and I could not connect to the server manually through the "Other Server..." button either.
Then I tried to manually copy the Time Machine backup (Backups.backupdb) to a partition of the new Mac mini. Although the destination on the new Mac mini is formatted to OS X Extended (Journaled), Finder.app complains, "The operation can't be completed because it isn't supported."
So at the very first step of the long winding road, I'm already stuck. Could anyone advice me how to copy the old server to new machine to inherit the server function without causing a disaster? At the moment I have three scenarios.
Copy Time Machine backup somehow (I need to know how, though!) to the second partition of the new Mac mini and then use Migration Assistant to import it. .... The backup is not the latest state of the old server, but most of data will be available. I don't need to stop the server while copying data (probably). Question is how to copy the backup file to the new desination.
Use Migration Assistant directly from the old server to the new server. (Have not tried yet).... Obiviously, I need to halt the server quit a long time to do this.
Just bluntly try to update the old server to El Capitan and install the new version of Server.app. Try to recover from Time Machine backup when failed. ... I thought this aproach is too risky.