I'm attempting to upgrade my backup server from Windows Server 2008 R2 Enterprise to Windows 2012 R2 Datacenter. I've attempted the upgrade twice so far and have, most likely, corrupted the process myself thru impatience! The process runs it's course and everything appears to be working but it's running for over 2 days and, after 1 full day of seeing "Preparing to Start" (or something to that effect), I get impatient and force a reboot which ends up telling me that the "upgrade failed"....Has anyone performed this upgrade successfully? If so, can you let me know if it typically takes more than 2 days and whether or not I should try it again with a little more patience. Thanks!
Much depends on what it is doing. Often in such a case, decide how long you are willing to wait.
Depending on the amount of data on your windows 2008, an option is to virtualize this system. install 2012 from scratch with hyper-v and attach a copy of the win2k8 's VHD/VHDx and try the process in the VM while allowing it to take as long as it needs.
dsik2vhd from Sysinternal's MS portal.
another clone it using vmware's converter and use the free ESX host to set it up for test....
You know what you may find if you let the process go which I've learned some time ago, is that it might have been an additional 20 minutes in the "Preparing to start"
This is a backup server to what and for what? If extended outage is unacceptable reconsider how to achieve what you need.
Does the hardware support win2k12?