Ubuntu-ltsp is not a mess! [ but needs some polish :) ]

Pierre Yann Baco pbaco at carlit.net
Thu Sep 11 13:07:23 BST 2008


My name is Pierre Baco. For the last 3 years I've installed LTSP based
solutions in approx 30 elementary schools for a total of +/- 700 thin 
clients (mainly recycled old fat pcs + PXE network boards).

First sites used woody+LTSP4.2. Last june, the local education 
department required all schools to be updated to Ubuntu Hardy + LTSP5. 
I've done so (inc. adding an extra 64Mb in some (too) thin clients) in 
august. Globally, the new solution runs fine. LTSP5 is easy to 
setup-configure, it supports a large set of hardware, local USB-sound 
works like a charm.

However, there is still a "mini" list of problems for which I've not 
found a complete and clean solution. I do known some of these problems 
are not directly linked to LTSP code/setup, but their effects have a 
deeper impact in a LTSP based site (and in schools where Msoft is a 
hard-to-break monopoly). Here is the list:

1°) ldm:
   - Not localized. This is a real issue in french (and I guess others) 
elementary schools. "Username" and "Password" are simple english words 
(and we french need to improve our english), but there should not be the 
first two words displayed by a computer in a french school.
   - NumLock off: Can't force NumLock ON prior to enter username and 
password. 8 years old kids (and their teachers...) always forget to 
press NumLock prior to enter their (often birtdhay date based) password, 
and login fails until they realize it (sometimes they don't!)
   - persistence of ldm screen after server shutdown or network failure: 
When the server is down (or the link between it and a thin client), ldm 
continues to ask gently for username/password "as usual". There's no way 
for a user to know something is wrong "on the other side". You can't 
imagine the number of support calls I get from users entering 20 times 
in a row their login/passwords (as they can't check the server status 
located elsewhere). With LTSP4.2, thin client gdm screens were 
locked-greyed out when the network or the server was down.

2°) PolicyKit:
   - Can't use GNOME administration utilities (users-admin etc.) on a 
thin client. (same happens within NX remote sessions). Works only on 
server console. It's also a real issue when the server is in a locked 
room. I've found a couple of threads about this, but could not find a 
real solution for it. I've tried almost all polkit-gnome-authorization 
configurations: still no success. And don't even think to ask a teacher 
to run useradd/userdel from command line to add 30 login names every 
Sept 1st....

3°) Process cleanup:
   - This list has received many posts about this (persistence of 
processes after thin client logouts). There are workarounds, but no real 
fix yet (or workaround included in a .deb update). My quick and dirty 
workaround: crontab based reboot every night.
   - same (gnome) problem with the ~/.gvfs still mounted after user 
logout. This generates a problem with userdel and/or other user 
administration utilities (can't delete user homedir).

4°) Sound compatibility with some educational programs:
  - ChildsPlay and tuxpaint are not very happy with remote sound (no way 
to quit the application except big red switch, (leaving CPU eating 
processes). There's a workaround (manually disable esound in the launch 
script), but it would be nice to have an add-on deb package (like 
"tuxpaint-ltsp.deb") to integrate the workaround in the general 
update/upgrade process.

Having this list fixed would eliminate 90% of problems encountered in 
the schools where I've installed Ubuntu+LTSP5.

No need to say I'm ready to help and contribute (more details, 
additional testing, translation, etc.)

And "Chapeau Bas" to those working hard to make Ubuntu+Ltsp the great 
solution it is today despite grumpy users like me.

Pierre Baco

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