[slurm-users] About x11 support

[Mahmood Naderan]

Hi Gareth,
Thanks for the info. My cluster is not a big one and I have configured in
the following way.
1- A frontend which has the rocks 7 (based on centos 7) with gnome. Users
login to this node *only* via vncviewer.
2- While a user is connected to his gnome desktop, he opens a terminal and
may run an interactive GUI job. So, he has to use x11.

Now, the question is, why the following error happens when we now that x11
support had been enabled during the compilation.

[mahmood at rocks7 ~]$ srun --x11 --nodelist=compute-0-5 -n 1 -c 6 --mem=8G -A
y8 -p RUBY xclock
srun: error: Cannot forward to local display. Can only use X11 forwarding
with network displays.


Regards,
Mahmood




On Fri, Nov 23, 2018 at 3:22 AM Williams, Gareth (IM&T, Clayton)
<Gareth.Williams at csiro.au> wrote:

> X11 comes up on this list now and then.  I'm often tempted to describe our
> site's approach and will do so now it case it help others (or someone wants
> to say why it is a terrible approach).
>
> First some preamble:
>  * we offer 'login' nodes with limits on what can be run as a
> highest-reliability option for managing batch jobs
>  * we offer a set of 'interactive' nodes where there is more flexibility
> for running larger analysis, development and house-keeping tasks.
>  * we offer a set of 'visualisation' nodes with gpus and setup for
> hardware accelerated graphics
>  * we encourage use of (vnc) virtual desktop sessions, and/or ssh access
>
> In both modes of access we ensure DISPLAY is set in a form that is network
> accessible within the cluster. ie _not_ localhost:NN
> With ssh this is done with the sshd_config X11UseLocalHost=no option.
>
> With DISPLAY set to a network accessible form and an xauth entry in the
> home directory, batch processes can access DISPLAY as long as the DISPLAY
> variable is passed into the job.
>
> No plugin, no compiled in support in slurm.
>
> Note that DISPLAY is not in a form immediately accessible outside the
> cluster (not fqdn of the external interface) and we have various firewalls
> in place.
>
> Gareth
>
>
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