= Remote rendering using VNC and !ParaView
Remote rendering is also possible using the Virtual Network Computing (VNC, e.g. [http://www.tigervnc.org TigerVNC] or [http://www.turbovnc.org/ TurboVNC]) package. We advice you to use the strudel application to access an interactive desktop session on JURECA. See section [wiki:vnc3d] for a detailed description of a VNC session on JURECA. 

Strudel provides you with the options
a. to login to JURECA - login node (vis:2xGPU) to run the vnc-server on a '''visualization login node''', or
b. to JURECA - compute nodes (vis 2xGPU) to run the vnc-server on JURECA's '''visualization batch nodes''': 

[[Image(StrudelSiteAuswahl.png)]]

|| '''connect to''' || || '''pro''' || '''contra''' ||
{{{#!td
  a. JURECA - login node (vis:2xGPU)
}}}
{{{#!td
[[Image(VNCOnVisLoginNode.png, 600px)]]
}}}
{{{#!td
 * rendering on GPU
 * large memory
 * no batch job needed
 * no accounting (unless you start a parallel pvserver)
 * pvserver may run in parallel on JURECA's [#SampleParaViewSessionJURECAComputeNodes compute nodes] or [#SampleParaViewSessionJURECAVisualizationNodes visualization nodes]
}}}
{{{#!td
 * resources shared between users
 * in case of pvserver running separately: the node pvserver is running on has to be explicitly specified in the Server Configuration Menu of the ParaView GUI
}}}
|-----------------------------------------------------------
{{{#!td
 b. JURECA - compute nodes (vis:2xGPU)
}}}
{{{#!td
[[Image(VNCOnVisComputeNode.png, 600px)]]
}}}
{{{#!td
 * dedicated resource
 * rendering on GPU
 * large memory
 * pvserver may (should!) run in parallel on JURECA's visualization nodes as described [#SampleParaViewSessionJURECAVisualizationNodes here].
 * ParaView GUI client and pvserver running on the same node, => connect to localhost:11111
}}}
{{{#!td
 * accounting
}}}

== Starting the !ParaView GUI on the remote desktop
In case you startet the VNC server with the option '-profile vis', your VNCViewer should look like this:

[[Image(VNCViewer.PNG, 800px)]]

Now, just double-click on the ParaView-Icon to start the ParaView client.

== [=#SampleParaViewSessionJURECAComputeNodes] Starting a pvserver on JURECA's compute nodes

In this section we show how to use ParaView's server side rendering capabilities on JURECA's '''compute nodes''' in a sample session step by step.
1. Open a terminal and load the modules providing the ParaView software
{{{
bash-4.2$ module load Stages/Current intel-para ParaView/5.0.1-OSMesa
}}}

2. Next, we allocate some resources for our ParaView server, and run the ParaView server (in this example session on 1 node, using 24 tasks)
{{{
bash-4.2$ salloc --partition=devel --nodes=1 --time=00:20:00
salloc: Pending job allocation 1711109
salloc: job 1711109 queued and waiting for resources
salloc: job 1711109 has been allocated resources
salloc: Granted job allocation 1711109
bash-4.2$ srun --nodes=1 --ntasks=24 pvserver
}}}

 which will produce the following output from the ParaView server:
{{{
Waiting for client...
Connection URL: cs://jrc0036:11111
Accepting connection(s): jrc0036:11111
}}}
 where 
{{{
jrc0036:11111 
}}}
 is the hostname and portnumber on JURECA the server will listen to.
3. As a next step, click the Connect button in the ParaView GUI and configure a server with the corresponding hostname and portnumber as described [wiki:SampleParaViewSessionJURECA#connectToServer here]

== [=#SampleParaViewSessionJURECAVisualizationNodes] Starting a pvserver on JURECA's visualization nodes

In this section we show how to use ParaView's server side rendering capabilities on JURECA's '''visualization nodes''' in a sample session step by step.
1. open a terminal and load the modules providing the ParaView software
{{{
bash-4.2$ module load Stages/Current intel-para ParaView
}}}
and set the DISPLAY environment variable as follows
{{{
bash-4.2$ export DISPLAY=:0.0
}}}
2. Next, we allocate some resources for our ParaView server (this step has to be omitted in case you started a VNC session on the visualization batch nodes via strudel, since strudel allready allocated some resources for you)
{{{
bash-4.2$ salloc -N 2 -p vis --gres gpu:2 --start-xserver     
}}}
 and run the ParaView server (in this example session on 2 nodes, using 48 tasks): 
{{{
bash-4.2$ srun --cpu_bind=none --ntasks=48 --gres=gpu:0 vglrun pvserver --use-offscreen-rendering
}}}

 which will produce the following output from the ParaView server:
{{{
Waiting for client...
Connection URL: cs://jrc1391:11111
Accepting connection(s): jrc1391:11111
}}}
 where 
{{{
jrc1391:11111 
}}}
 is the hostname and portnumber on JURECA the server will listen to.
3. As a next step, click the Connect button in the ParaView GUI and configure a server with the corresponding hostname and portnumber as described [wiki:SampleParaViewSessionJURECA#connectToServer here]