Xubuntu 16.04 with read only root filesystem for SSD disk
----------------------------------------------------------

* example:
    /dev/sda: HDD disk (mechanical disk)
    /dev/sdc: SSD disk (solid state disk)

    /dev/sda2: /home /tmp /var/tmp
    /dev/sda3: swap
    /dev/sdc1: /

* install xubuntu 16.04 in /dev/sdc1.

* boot with xubuntu 16.04 in /dev/sdc1.

* mount /dev/sda2 /mnt

* mkdir /mnt/tmp ; chmod 1777 /mnt/tmp

* mkdir /mnt/home ; chmod 0755 /mnt/home

* mkdir -p /var/mounts/sda2 ; chmod 0755 /var/mounts/sda2

* mkdir -p /var/mounts/mediarw ; chmod 0755 /var/mounts/mediarw

* mkdir -p /var/mounts/mediaro ; chmod 0755 /var/mounts/mediaro

* mkdir -p /var/mounts/mediaro/share1 ; chmod 0755 /var/mounts/mediaro/share1

* mkdir -p /var/mounts/log ; chmod 0775 /var/mounts/log ; chown root.syslog /var/mounts/log

* mkdir -p /var/mounts/lightdm ; chmod 0755 /var/mounts/lightdm ; chown lightdm.lightdm /var/mounts/lightdm

* rsync -av /home/ /mnt/home/

* rm -fr /home/* ; rm -fr /home/.*  <-- CAUTION!

* rm -fr /tmp/* ; rm -fr /tmp/.*

* rm -fr /var/tmp/* ; rm -fr /var/tmp/.*

* rm -fr /var/log/* ; rm -fr /var/log/.*

* rm -fr /var/spool/* ; rm -fr /var/spool/.*

* rm -fr /var/lib/blueman/* ; rm -fr /var/lib/blueman/.*

* rm -fr /var/lib/lightdm/* ; rm -fr /var/lib/lightdm/.*

* rm -fr /var/lib/lightdm-data/* ; rm -fr /var/lib/lightdm-data/.*

* /etc/fstab
    #--- root & swap ---
    UUID=[UUID-SDC1]        /                       ext4    ro,noatime,errors=remount-ro    0   1
    UUID=[UUID-SDA3]        none                    swap    sw                              0   0

    #--- home & tmp ---
    UUID=[UUID-SDA2]        /var/mounts/sda2        ext4    rw,noatime,errors=remount-ro,x-systemd.requires=/   0   1
    /var/mounts/sda2/home   /home                   none    bind,x-systemd.requires=/var/mounts/sda2            0   0
    /var/mounts/sda2/tmp    /tmp                    none    bind,x-systemd.requires=/var/mounts/sda2            0   0
    /var/mounts/sda2/tmp    /var/tmp                none    bind,x-systemd.requires=/var/mounts/sda2            0   0

    #--- logs ---
    tmpfs                   /var/mounts/log         tmpfs   rw,nosuid,nodev,noatime,mode=0777,size=8M,uid=root,gid=syslog,x-systemd.requires=/  0   0
    /var/mounts/log         /var/log                none    bind,x-systemd.requires=/var/mounts/log                                             0   0
    /var/mounts/log         /var/spool              none    bind,x-systemd.requires=/var/mounts/log                                             0   0
    /var/mounts/log         /var/lib/blueman        none    bind,x-systemd.requires=/var/mounts/log                                             0   0

    #--- lightdm ---
    tmpfs                   /var/mounts/lightdm     tmpfs   rw,nosuid,nodev,noatime,mode=0755,size=1M,uid=lightdm,gid=lightdm,x-systemd.requires=/  0   0
    /var/mounts/lightdm     /var/lib/lightdm        none    bind,x-systemd.requires=/var/mounts/lightdm                                             0   0
    /var/mounts/lightdm     /var/lib/lightdm-data   none    bind,x-systemd.requires=/var/mounts/lightdm                                             0   0

    #--- media ---
    tmpfs                   /var/mounts/mediarw     tmpfs   rw,nosuid,nodev,noatime,mode=0755,size=1M,uid=root,gid=root,x-systemd.requires=/                                0   0
    aufs                    /media                  aufs    rw,noatime,br=/var/mounts/mediarw=rw:/var/mounts/mediaro=ro,udba=reval,x-systemd.requires=/var/mounts/mediarw   0   0

    #--- shares ---
    [NFSSERVER]:/path/to/nfs/share1  /media/share1  nfs     _netdev,rw,noauto,user,users,noexec,nosuid,nolock,noatime,nfsvers=3,sec=sys,udp,rsize=32768,wsize=32768     0   0

* /etc/default/grub
    GRUB_TIMEOUT=N
    GRUB_RECORDFAIL_TIMEOUT=$GRUB_TIMEOUT
    update-grub

* /usr/local/bin/remountrw + chmod 744
    mount -o remount,rw /

* /usr/local/bin/remountro + chmod 744
    sync
    sleep 1
    mount -o remount,ro /

* Network Manager: wired connection with fixed IP address:
    "/etc/NetworkManager/system-connections/Wired Connection" + chmod 600

        [ethernet]
        duplex=full
        mac-address=xx:xx:xx:xx:xx:xx

        [connection]
        id=Wired Connection
        uuid=66b010e7-d2b0-4e5a-a2d8-f1d8191a241d
        type=ethernet
        timestamp=1440124541

        [ipv6]
        method=auto
        ip6-privacy=0

        [ipv4]
        method=manual
        dns=<IP_ADDRESS>;
        address1=<IP_ADDRESS>/<MASK 0-30>,<DEFAULT_GATEWAY>
        may-fail=false

* Issues:
    * The guest session not work: /etc/password and /etc/shadow are read only.
    * Lightdm can not remember the last user logged.