[vox] LTSP.

[Henry House]

På tisdag, 21 september 2004, skrev Don Werve:
> I'm looking at setting up a terminal server, and have a question about 
> LTSP that doesn't seem to be covered by the docs; namely, when one logs 
> out of an LTSP session on the client, is that session destroyed, or kept 
> running?

That depends on whether the login was through VNC or the plain old X
protocol.

> I'd like to set up my environment such that the users can, say, 
> experience a power failure on the terminals, with the server sitting on 
> a UPS, and when the power comes back up, the users can just log back in 
> and resume where they left off.  Basically, I'd like to set up a Sun Ray 
> type environment, only using Debian.
> 
> Any ideas, or am I barking up the wrong tree?

I have set this up at my office. It works this way:

1. The thin clients boot up normally and get a display manager from the
   server. The display server is WDM but GDM should be okay too.

2. In addition to the standard login options in WDM's menu (IceWM,
   Gnome-session, failsafe, etc) there is an option for VncSelector. The
	user must choose this.

3. The VncSelector program, written by Doug Barbieri, is a GUI with buttons
   to create a new VNC virtual display and to attach to an existing one. If
	there is no old virtual display then the user must create a new one.

4. The user selects the desired virtual display (there can be many), which
   VncSelector passes as an argument to an invocation of xvncviewer.

5. Xvncviewer runs in fullscreen mode on the terminal server machine, being
   displayed on the thin client as a remote X client program.

6. If the power fails on the client or the user switches it off, the Vnc
   virtual display with all the users' apps keeps running and may be
	retrieved by going back to step 4.

Problems with this set-up are that is not extremely fast, that many GUI
applications are not designed to stay running for weeks on end, and that the
VNC virtual display may not match the resolution of the thin client's
monitor if it was created at a different thin client with a different
monitor resolution. The speed could be improved by running xvncviewer
directly on the thin client machine, but in this case it is fiddly to get
the authentication file and the VNC display number. VncSelector does not do
this so you must currently do it manually.

I hope this helps.

-- 
Henry House
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