added gui

gui/gui.md

+
+----
+
+===== Graphical Applications =====
+
+Running graphical applications interactively
+
+  * is an important feature on our clusters
+  * is not a usual feature of HPC clusters
+  * because it also makes things complicated
+    * how/where to display the graphics
+    * scheduling of interactive jobs
+
+
+----
+
+===== Xpra =====
+
+  * is the tool we use for graphical applications
+  * in addition to VNC
+  * see [[06_background_info.html#(3)|Background information]] slides for more technical details
+
+
+----
+
+===== start VNC desktop =====
+
+  * start VNC server (e.g. on login node 1):
+
+<code>
+vncserver -geometry 1920x1080 -depth 24  :display-number
+</code>
+  * use UID (user id) minus 30000 as display-number
+  * MATE desktop (is a fork of Gnome 2) is preconfigured in ''%%~/.vnc/xstartup%%''
+  * connect your VNC-viewer to address ''%%mul-hpc-81a.unileoben.ac.at:display-number%%''
+    * or ''%%mul-hpc-81b%%'' for login node 2
+
+
+----
+
+===== Xpra overview =====
+
+  * Xpra server runs on same compute nodes as application
+    * it is started together with application in job script
+    * each application has a dedicated Xpra server
+  * the display can be detached and reattached any time
+
+
+----
+
+===== Job script =====
+
+==== example for Abaqus CAE 2017 ====
+
+<code>
+#!/bin/bash
+#SBATCH --partition E5-1650
+#SBATCH --qos=E5-1650-inter
+#SBATCH --nodes=1
+#SBATCH --ntasks-per-node=1
+#SBATCH --mem=15G
+#SBATCH --job-name=abqcae
+
+abq=/opt/sw/x86_64/generic/abaqus/Commands/abq2017
+
+xpra start                 \
+  --daemon=no              \
+  --exit-with-children=yes \
+  --start-child="$abq cae -mesa" 
+</code>
+
+----
+
+===== Job script =====
+
+==== example for Fluent 17.1 ====
+
+<code>
+#!/bin/bash
+#SBATCH --partition E5-2690v4
+#SBATCH --qos=E5-2690v4-inter
+#SBATCH --nodes=1
+#SBATCH --ntasks-per-node=14
+#SBATCH --mem=30G
+#SBATCH --job-name=fluent171
+
+fluent=/opt/sw/x86_64/generic/ansys_inc/v171/fluent/bin/fluent
+
+xpra start                 \
+  --daemon=no              \
+  --exit-with-children=yes \
+  --start-child="$fluent 3ddp -t1" 
+
+</code>
+
+----
+
+===== attach display =====
+
+  * to see the graphical output you must attach to the Xpra server
+    * use ''%%sbatch+display%%'' to submit and display a job
+    * use ''%%display JOBID%%'' to display job with given JOBID
+    * use ''%%display-all%%'' to display graphical output of all your jobs
+
+
+----
+
+===== detach display =====
+
+  * the display can be detached and reattached any time
+  * to detach the display:
+    * use ''%%undisplay JOBID%%'' for one JOBID
+    * use ''%%undisplay-all%%'' for all your jobs
+    * or use symbols on the upper right side of MATE desktop
+
+
+----
+
+===== attach/detach display =====
+
+Live demonstration.
+
+
+----
+
+