RE: Preventing X server resets

["Oliver, Peter" <peter dot oliver at aquila-networks dot co dot uk>]

> -----Original Message-----
> From:	Harold L Hunt II [SMTP:huntharo@msu.edu]
> Sent:	Friday, November 15, 2002 7:12 PM
> To:	cygwin-xfree@cygwin.com
> Subject:	Re: Preventing X server resets
> 
> Peter,
> 
> Let me rephrase your question and ask you if it makes sense:
> 
> ``If I am talking on the phone to my mother and she unplugs her phone, 
> can I just continue talking to her?''
> 
Yes, but if Dad is on the other extension at the same time I would expect to
be able to continue talking to him :-)

Perhaps I wasn't clear in my question.  I know that if a machine is rebooted
then any X clients running on it will be lost.  As an aside, I also know
that if a machine running an X server is rebooted then the server is lost,
and there's typically no way to tell the clients where to reconnect to; the
RandR extension will apparently change this in the future.

However, I have X clients running on many machines and all displaying on the
same server.  If most of these hosts go down then the clients on that host
are lost, but the X server keeps running and the other clients are
unaffected.  If the host I logged into with XDMCP goes down, the X server
resets and kicks off all the other clients which are otherwise fine.  It's
this behavior that I wish to avoid.

> The answer is no.  You have established a connection with a server that 
> is supposed to manage your X session... if that server fails, or if the 
> connection to it is unreliable, then you X Session is terminated. 
>  Unfortunately, the way the system is designed is that applications you 
> launch from your X session are managed by the remote XDMCP machine... if 
> that machine goes down there is no way to transfer control of those 
> applications to another machine.
> 
I don't believe that this is true.  As I understand it, X11 clients connect
directly to the X11 server.  Checking with netstat, I see that there are no
connections between the host that I logged into with XDMCP and another host
running an xterm.

I know that what I asked is possible in general, since an X server called
PC-Xware does it.  When XDMCP goes away it asks something like "Your XDM
session has ended.  Would you like to reset the X server?", and if you say
no you can just carry on working.  I hoped that I'd be able to do the same
thing with XFree86.

> 3) If you can't do anything about the machine or the network, then you 
> need to adjust your quality-of-service expectations.
> 
Perhaps this is the best suggestion.  I can usually run a session for weeks
or months without incident, so perhaps I'm asking too much :-)

Alternatively, it occurs to me that I could start my session using rlogin
rather than XDMCP.  Fiddly, but it should do the trick.

-- 
Peter Oliver
Midrange Services
Aquila Networks Services Ltd


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