HP Scalable Visualization Array Software - Manual (Page 29)

1. Allocate: Allocates cluster resources for the visualization job.
The allocation phase launches an HP XC SLURM job using the srun command. A SLURM Job ID is
assigned to the job, which starts a session with the appropriate cluster resources; for example, the
Display Surface and the requested number of display and render nodes. The number of resources can
be specified using command line options in the script.
2. Launch: Starts the visualization session and necessary services on the render and display nodes; for
example, X Servers and DMX.
3. Run: Starts the master application component on the display node and the worker application components
(if any) on the render nodes and display nodes. The run phase also starts any Chromium components,
if appropriate to the job. Where the master runs is based on the Execution Host value in the Configuration
Data Files. This varies based on the Display Surface you choose for the job. See the
SVA System
Administration Guide for detailed information on the Configuration Data Files and Display Surfaces.
4. Terminate: Stops the visualization session cleanly. Also stops the services that were started by the script;
for example, X Servers and DMX.
Using a Script to Launch an Application
After modifying the template (if necessary) to create a launch script that matches the application requirements,
start the script from the head node. Each template has default options that you can respecify. These options
are documented in the
SVA Visualization System Software Reference Guide, and in manpages for each
template or fully functional script.
The following command runs the atlantis application on the FULL_DISPLAY Display Surface using the
Chromium/DMX launch script. The application-specific command-line parameter -count 20 is used.
% sva_chromium_dmx.sh -d FULL_DISPLAY \
"/usr/X11R6/lib/xscreensaver/atlantis -count 20"
This script command uses the FULL_DISPLAY Display Surface (a site-specific multi-tile Display Surface),
allocates the resources, and starts the X Servers. You do need to enter the name of an existing Display
Surface on your cluster as a command option.
A Display Surface is a named assemblage of one or more display devices with a particular orientation and
their associated display nodes. Initial configuration of the SVA creates a named single tile Display Surface
for each display node and its associated display device. Your site administrator may have created additional
Display Surfaces using the Display Surface Configuration Tool. The site administrator also can use the Display
Node Configuration Tool to specify which (if any) display nodes output more than one tile. This is the way
the FULL_DISPLAY Display Surface in this example was created. You can use the Display Surface
Configuration Tool to list all the named Display Surfaces on your cluster. Both tools are documented in the
SVA System Administration Guide.
Running an Interactive Session
Use the Chromium/DMX launch script to interactively control the launching of your applications.
You must set the DISPLAY environment variable correctly before you launch the script, or it fails. You set
the DISPLAY environment variable to point to the node's X Display where the DMX Console Window
appears. (Refer to the DMX documentation for details of its user interface, including the DMX Console
Window.) For example:
% export DISPLAY node:0.0
Use the following command to launch an interactive session:
% sva_chromium_dmx.sh -I -d FULL_DISPLAY
This script command uses the FULL_DISPLAY Display Surface (a site-specific multi-tile Display Surface),
allocates the resources, and starts the X Servers. It also starts a desktop environment (for example, KDE or
Gnome) from which you can launch applications repeatedly while retaining the same job resources. To
launch an application, open a terminal window and then run the application as usual.
In the specific case of OpenGL applications, you use the Chromium/DMX script again from the terminal
window to run it. For example:
% sva_chromium_dmx.sh "/usr/X11R6/lib/xscreensaver/atlantis -count 20"
Running an Interactive Session 29