Cool Solution - XenApp/XenDesktop on Thinclient with only 1GB Flash
From Univention Wiki
Thin Clients may have smaller storage devices (i.e. Compact Flash or onboard Flash) than the default 1,2G of the UCC default image.
This is an example for a thin client image for 1GB Flash supporting XenApp.
The configuration file, tested on a HP t5745(1GB), can be found at the bottom of this article.
Software packages required
Here we are going to create a small UCC Thin Client image targeting full Citrix support, tested in a HP t5745 with 1GB flash storage.
In a typical deployment, some of our customers often require these features in order of priority:
- XenApp Session (+Firefox), including german localisation
- Typical ressoures: Sound, Flash, HDX
- if possible special enhancements: truecrypt
- if also possible RDP session as a fallback
For this we are going to need two diferent approaches, first we will use the ucc-image utility to build an image with an edited configuration file, and second we manually will install the packages left from the previous step.
Step 1 - Configuration File
This file is based on the official file for a thin client
Please read UCC Manual Generation of adapted images.
The official images are also explained here
Another configuration file to generate a <1GB image 
The image size is set at 790MB:
# Image size in GB size: 0.794
A graphical system is still installed, but without desktop manager:
univention-lightdm (Integration of lightDM login manager into UCC) indicator-session (Session management, status and user switching) indicator-power (Power state)
X window system (and input drivers)
xserver-xorg xserver-xorg-input-mouse xserver-xorg-input-kbd
Drivers for some video card families
xserver-xorg-video-ati xserver-xorg-video-intel xserver-xorg-video-vesa
Tools: (no sessions are installed in this step)
openssh-server (Remote secure shell (SSH) server) language-pack-de ntpdate (client for NTP time servers)
Integration with the UCC domain, always required:
univention-ucc-theme (Univention theme) univention-corporate-client (Metapackage for client systems)
This packages will be installed :
# Kernel linux-image-generic (Linux kernel image) # Grub univention-ucc-grub (Grub2 configuration)
/boot is set to 45MB. This is usually enough for one kernel, meaning that kernel updates should be performed by generating the image once again.
partition2_name: boot partition2_size: 45 partition2_fs: ext4 partition2_mountpoint: /boot
The slash partition (/) will take all the available space.
partition3_name: root partition3_size: expand partition3_fs: ext4 partition3_mountpoint: /
The GPT would start at 2MB for alignment, and it will use 10MB of space. No "swap" partition is considered.
Now, after calling ucc-image -c thinclient-image-1G.cfg we will get the initial image
let's say in /tmp/tmprUgkUj/ucc-1.0-rev2-thinclient-image-1G.img*
2 Step - Manual installation of extra packages
The idea is to first free some space in used by apt-get and then temporarily mount additional disks so we get enough cache for packages.
That is to delete the cache of packages in
var/cache/apt/ (be sure the 'archives/partial' directory is there)
and the lists in
/var/lib/apt/lists/ (there should remain a 'partial directory in here' as well)
for that we will create two temporary filesystems
dd if=/dev/zero of=/tmp/cache-apt bs=1M count=500 && mkfs.ext4 -F /tmp/cache-apt dd if=/dev/zero of=/tmp/apt-lists bs=1M count=500 && mkfs.ext4 -F /tmp/apt-lists
Now they can be mounted First let us mount the image in /mnt/img/
mkdir /mnt/img mount -o loop /tmp/tmprUgkUj/ucc-1.0-rev2-thinclient-image-1G.img /mnt/img/
and free some space:
apt-get clean rm /var/lib/apt/lists/appcenter* rm /var/lib/apt/lists/univention*
Second, let us mount the extra filesystems
mount -o loop /tmp/cache-apt /mnt/img/var/cache/apt/ mkdir -p /mnt/img/var/cache/apt/archives/partial mount -o loop /tmp/apt-lists /mnt/img/var/lib/apt/lists/ mkdir /mnt/img/var/lib/apt/lists/partial
with all ready, we can go into the image
Once inside we can install xenapp session (~200MB in this case)
apt-get install --no-install-recommends univention-ucc-session-xenapp apt-get clean
Now the image is full
sync exit umount /mnt/img/var/cache/apt/ umount /mnt/img/var/lib/apt/lists/
Thanks to the 50MB buffer that the image has other utilities as flash player, the xen package can later be added for the user itself. This is also necesary since the user has to agree with the respective licenses of these programs.
- 794MB image configuration file