# install packages
apt-get install -y ltspfs
# libfuse2 fuse-utils

# all all user to group fuse
for USER in $(ls /home/); do
    if [ $USER != "lost+found" ]; then
        usermod -a -G fuse $USER
    fi
done

# load fuse module on boot
cat /etc/modules | grep fuse || echo fuse >> /etc/modules

# modify ltsp configuration
echo "LOCAL_STORAGE=Y" >> /var/lib/tftpboot/ltsp/*/lts.conf

Debug

# client
/usr/sbin/ltspfs_mount
/usr/sbin/ltspfs_mount /dev/sdd1

# server
share/ldm/rc.d/X10-delayed-mounter:
/usr/sbin/ltspfsmounter

# usb disk mount on server when user logen in
/tmp/.${USER}-ltspfs/

Links
https://wiki.ubuntu.com/DebugLocalDev