Upgrade ODROID-XU4 to OpenMediaVault 3

This short tutorial will show you how to upgrade a ODROID-XU4 running OpenMediaVault 2 to OpenMediaVault 3.
OMV 3 (Erasmus) uses Debian 8 (Jessie) instead of 7 (Wheezy). So alongside OMV you will get new packages as well.

1. Make a backup of your current installation!
2. Make sure your system is up-to date by running:

   apt-get update && apt-get upgrade

3. Reboot
4. Uninstall all plugins including the OMV-Extras package
5. Before you upgrade you should change your boot.ini and /etc/fstab.
   Mount your boot partition like this:
   

   mkdir /media/boot
   mount /dev/mmcblk0p1 /media/boot

6. Then edit your /media/boot/boot.ini and change ro to rw in the setenv line. The line should look like below:
   

   setenv bootrootfs "console=tty1 console=ttySAC2,115200n8 root=UUID=<YOUR_ROOTFS_UUID> rootwait rw fsck.repair=yes"

7. Record your rootfs UUID
8. Afterwards edit your /etc/fstab and add the following above the openmediavault volumes:
   

   # UNCONFIGURED FSTAB FOR BASE SYSTEM
   UUID=<YOUR_ROOTFS_UUID> / ext4 errors=remount-ro,noatime,nodiratime 0 1
   # >>> [openmediavault]
   [...]

9. Finally run

   omv-release-upgrade

   and reboot afterwards
10. Now you can install the OMV-Extras package for OMV 3 and your plugins again:
    

    wget http://omv-extras.org/openmediavault-omvextrasorg_latest_all3.deb
    dpkg -i openmediavault-omvextrasorg_latest_all3.deb
    apt-get update