Virtual Distro Dispatcher (VDD) is a lightweight Desktop-as-a-Service solution that uses virtualization to project multiple operating system instances onto terminals across a network. VDD consists of LTSP for terminal services and the Xen virtualization system. It allows obsolete PCs or thin clients to access full desktop environments from a more powerful central server, improving performance, scalability, and reducing hardware costs compared to purchasing new PCs. The latest version of VDD uses Xen virtualization for improved performance and the ability to run Windows and other non-Linux operating systems as virtual machines.

5. Virtualization constraints 1/2 C1 – Open Source Software C2 – HVM support C3 – Quick and easy to restore C4 – Simmetric Multi Processing (SMP) OS guest support C5 – User level kernel execution C6 – Integrated VNC Server

6. Virtualization constraints 2/2 C1 C2 C3 C4 C5 C6 VMware ✔ ✔ ✔ ✔ Virtualbox ✔ ✔ ✔ UML ✔ ✔ ✔ Qemu ✔ ✔ ✔ ✔ ✔ XEN ✔ ✔ ✔ ✔ ✔

9. How to dispatch Linux on terminals 1) Start your VM from the VDD central station 2) Start Xephyr (Xephyr -fullscreen -ac :1) on a thin client 3) Export the DISPLAY variable within the VM: export DISPLAY=”ip_of_vdd:1” 4) startkde or gnome-session from the VM 5) Enjoy your dispatched distribution As regard OS like Windows, VNC protocol can be used.

10. VDD Architecture

11. A simple (localhost) example

13. Only Linux could be virtualized

14. User level kernel execution

15. UML development is slow and poorly documented

17. Paravirtualization and HVM support

18. Other operating system (e.g. Ms. Windows or ReactOS) can be virtualized now !! (HVM mode)

19. High performance virtualization allows to run Windows XP and Vista on very old PCs (80486 – Pentium) (not recommended but possible)

20. Something about performances 1/3 A CPU-bound test: John The Ripper

21. Something about performances 2/3 A filesystem latency test: lat_fs

22. Something about performances 3/3 A memory mapping test: bw_mmap_rd (open2close)

24. Buy 1 next generation VDD Server + 10 Trashware diskless thin clients for free (hardware: -83% ; Energy*: -18.5% )

25. Buy 1 next generation VDD Server + 10 mini ITX stations (hardware: -72% ; Energy*: -71.4% ) * Ref. www.eu-energystar.org/it/it_007c.shtml. Each thin client is considered to be powered on 6h per day.

31. Links and contacts The official Virtual Distro Dispatcher website: e-mail: info@vdd-project.org www: http://www.vdd-project.org Salvatore CRISTOFARO e-mail: cristofaro@dis.uniroma1.it Flavio BERTINI e-mail: flavio.bertini@dis.uniroma1.it D. Davide LAMANNA e-mail: davide.lamanna@dis.uniroma1.it www: http://www.dis.uniroma1.it/~lamanna Roberto BALDONI e-mail: roberto.baldoni@dis.uniroma1.it www: http://www.dis.uniroma1.it/~baldoni