If you are coming to Fedora from Ubuntu you may be surprised that installing the package doesn’t automatically start the SSH daemon on boot. We can change this with the following command, run as root:
systemctl enable sshd.service
The next time you boot your SSH server should have started automatically.
We had a situation recently where a customer was experimenting with XenServer 6.2 and Ubuntu VMs; he accidentally powered off the VM during a distribution upgrade and the VM would only boot with a read-only filesystem. Loading an ISO into the virtual CD drive didn’t do the trick; there’s no obvious way of booting to another medium during the boot process.
The trick is to boot into recovery mode; when the VM is powered off, select it and follow the menus like so:
VM -> Start/Shutdown -> Start in Recovery Mode
The VM should now boot to your Live CD/Rescue CD/etc.