graphic dump on cluster

[js2615 at columbia.edu]

Thanks for the prompt reply.  This is truly a great alternative.
I have followed the instructions, and it worked for me by using
-display frontend:10.0 option.

I understand that the Petsc graphic output is mainly for debugging
(which should probably be done just on my laptop), but I guess it
is helpful to have the functionale of dumping output on multiple
processors, even just for a fun demo.

Aron: In the original setup, my DISPLAY variable is set to
$DISPLAY=localhost:0.0.  This works indeed when I only use -np 1 (I
guess it only start the work on the master node n0000).

Cheers,

Jianing

> 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
>
>