Hi,
I have a Pi + external USB drive running as a home server, along these lines.
I started with the wheezy image. This morning I upgraded to jessie by editing the *.list files and running the following:
sudo apt-get update sudo apt-get upgrade sudo apt-get dist-upgrade
It seemed to be fine until the reboot. Looking around on the WWW, I found something about a bug in a recent kernel that kept root=PARTUIID=... in cmdline.txt from working, so I plugged the SD card into another computer and changed it to root=/dev/sda1 (there's only 1 USB drive attached, so it will always be sda). I think that got it pingable but it still wasn't ssh-able, so I had to plug a keyboard & monitor into it. It always ends up in the emergency shell with no ssh, but when I type 'systemctl default' at the keyboard it ends up working fine, but I have to it again after a reboot.
This mini-server is supposed to be headless in a cupboard, not attached to the TV in the living room, so I need to get it to boot fully unattended again. I've tried the following:
commenting out the swap & tmpfs entries in /etc/fstab (they point to encrypted partitions that come from /etc/crypttab) disabling dphys-swapfile blacklisting the cfg80211 module (the server uses only wired networking) I'm running out of ideas & haven't found anything in the syslog, although I'm not entirely sure what to look for.
Any suggestions?