graphic dump on cluster

[Satish Balay]

On Wed, 24 Jan 2007, Aron Ahmadia wrote:

> Is there a good script lying around somewhere for setting the X11
> connections up from the master/interactive node?  This seems like it could
> be a huge pain if you've got a bunch of worker nodes sitting in a private
> network behind the master in classic Beowulf style and you don't have a
> systems administrator to set it up for you.

Different clusters have different 'scripts' for job submission. So
you'll have to figureout how to 'sneak' in the ssh-x11 connections in
here during the job startup. [i.e this not easy to automate]

And then there are issues of x11 authentication & ssh authentication
to worry about [if we are opening sockets connectins across machines]

However there is a simple alternative to get this working - it the
following are true for your cluster:
- all compute-nodes share home filesystem with the frontend-node [i.e
  everyone can read the same ~/.Xauthority file for x11 permissions]
- a willing sys-admin who can change sshd config on the front-end. The
change is to add the following to /etc/ssh/sshd_config and restart sshd

>>>
X11UseLocalhost no
<<

With the above config - one can get X11 working as follows:
-  compute nodes directly talk via x11 to the front-end
-  the frontend forwards this x11 communication to the users desktop
   via ssh.

i.e you would do the following:
- login to frontend node from your desktop with ssh-x11 [ssh -Y frontend].
- Check what the display is [echo $DISPLAY]. It should be
  frontend:10.0 or something equivalent.
- Now run the PETSc executable with the option [-display frontend:10.0]

There might be some firewall issues that need to be taken canre of
[the x11 connections from compute-nodes to front-end should not be
blocked by the firewall]

Satish