Changes between Initial Version and Version 1 of vnc3d/manual

Timestamp:

05/03/16 22:45:54 (8 years ago)

Author:

Jens Henrik Goebbert

Comment:

--

vnc3d/manual

@@ +1 @@
+
+
+== ...
+== Manual Access ...
+VNC follows a very general approach, where a remote graphical desktop on one node of the remote cluster is started. \\
+On the user's workstation only a lightweight VNC viewer has to be installed. \\
+The graphical screen of the remote desktop is send as an image from the cluster to the viewer on the fly.
+
+The user can work with this remote graphical desktop in the usual way, just by interacting with keyboard and mouse. \\
+This is a very convenient way to work on a remote machine, not only for data visualization.
+
+VNC offers the ability to detach from a session (running in a VNC server) and then attach back at a later time. \\
+That means, that the user can close the VNC viewer on his/her computer and any application started in the VNC session on the server keeps on running - they do not pause or even be killed. \\
+Later on the user can connect back to the same VNC session (even from a different computer) and keep on working. \\
+
+[[Image(Trac_Setup_VNC.png, 640px)]]\\
+
+==== hardware accelerated rendering (OpenGL) 
+[[Image(https://upload.wikimedia.org/wikipedia/commons/thumb/6/67/X11transport.png/600px-X11transport.png, 200px, align=right, margin=0)]]
+Whenever an OpenGL capable visualization software, like !VisIt, is started on the remote cluster node, \\
+OpenGL commands can be redirected to the GPU of this node with the help of [http://www.virtualgl.org VirtualGL]. \\
+* ... using '''vglrun''' (e.g. vglrun paraview)
+This way the hardware accelerated rendering capabilities of a cluster node (if available) can be exploit for remote rendering. \\
+(attention: __without__ VirtualGL software, rendering using the CPU instead of the GPU must be used (if available), which is much slower).
+
+==== ok, what do I have to do?
+Using VNC requires three general steps.
+1. '''Prepare your account''' on a JURECAVIS node.
+2. '''Start a VNC server''' on a JURECA node.
+3. '''Tunnel VNC traffic''' to your workstation.
+4. '''Start a VNC viewer''' on your workstation and connect to the VNC server.
+
+\\
+=== 1. Prepare your account ...
+Before you use VNC '''for the first time''' you have to prepare your account:
+* login to a JURECAVIS node
+* create the directory ~/.vnc
+* define VNC password
+{{{ #!sh
+ssh <USERID>@jurecavis.fz-juelich.de
+mkdir ~/.vnc
+vncpasswd
+}}}
+
+\\
+=== 2. Start VNC server ...
+The following steps are necessary to start a VNC server on JURECA. \\
+Please notice that you have two general options:
+
+You can start the VNC server ...
+* ... on an '''interactive vis login node'''
+ * + no batch system == instant access
+ * -- system is shared with other users
+* ... on a '''dedicated vis node'''
+ * + system is not shared (exclusive use)
+ * -- access through batch system
+
+
+
+In case the VNC server could successfully be started (details in 1a,b), you will find a simular line in the output:
+{{{ #!sh
+Desktop 'TurboVNC: jurecavis02.fz-juelich.de:1 (profile <PROFILE>)' started on display jrc1384:1 (jurecavis02.fz-juelich.de:1)
+}}}
+
+Two important informations have to be taken from this output \\
+to setup the required SSH tunnel (with the correct network port) to the allocated node in step 2:
+1. The allocated node is '''jurecavis02'''
+2. The number of the VNC display is ''':1'''
+
+It is very important to know that the network port of the VNC server depends on this display number. \\
+The actual port number is 5900+<VNC display>, therefore port '''5901''' must be tunneled in this case.
+
+Important notes:
+* To ensure VNC sessions are not forgotten and keep on running forever, they will be '''killed after 24 hours ''' (WITHOUT warning).
+* Logout from your VNC session, after you have finished your work. This will save resources and close the VNC server. \\
+* If you start the VNC server the first time, you will be asked for a password (which is stored in ~/.vnc/passwd). \\
+  You will be asked for this password by the VNC viewer, when you connect to the VNC server. \\
+  To reset the password just delete the file ~/.vnc/passwd.
+
+==== a. ... on an interactive vis login node
+Open a SSH shell on an interactive vis login node (jurecavis.fz-juelich.de):
+{{{ #!sh
+ssh <USERID>@jurecavis.fz-juelich.de
+}}}
+
+Start your own VNC server on jurecavis.
+Usefull vncserver parameters are:
+* -profile        -> choose a profile (eg. -profile vis)
+* -geometry       -> set the screen size (eg. -geometry 1920x1080)
+{{{ #!sh
+# start the VNC server on visualization login node
+vncserver -profile vis
+
+...
+Desktop 'TurboVNC: <NODE>:<DISPLAY> (profile <PROFILE>)'
+ started on display <NODE>:<DISPLAY> (<NODE>:<DISPLAY>)
+...
+}}}
+
+==== b. ... on a dedicated vis node
+Open an SSH shell on any login node of JURECA the usual way:
+
+{{{ #!sh
+ssh <USERID>@jureca.fz-juelich.de
+}}}
+
+salloc is used to request an allocation.\\
+When the job is started, a shell (or other program specified on the command line) is started on the submission host (login node). \\
+From the shell srun can be used to interactively spawn parallel applications. \\
+The allocation is released when the user exits the shell.
+
+To allocate a vis node with 512 GByte main memory for one hour, use:
+{{{ #!sh
+# request allocation and spawn VNC server on visualization node
+salloc -N 1 -p vis --gres=mem512,gpu:1 --start-xserver --time=1:00:00
+srun -n 1 --cpu_bind=none --gres=gpu:1 vncserver -fg -profile vis -geometry 1920x1080 
+
+...
+Desktop 'TurboVNC: <NODE>:<DISPLAY> (profile <PROFILE>)'
+ started on display <NODE>:<DISPLAY> (<NODE>:<DISPLAY>)
+...
+}}}
+
+salloc/srun options
+* -N 1            -> Set number of requested nodes.
+* -p vis          -> Limit request to nodes from the visualization partition.
+* --gres=mem512   -> Set the size of main memory per node (mem512 or mem1024).
+* --gres=gpu:2    -> Set the number of requested GPUs in the range of 0-2.
+* --start-xserver -> Start an Xserver for usage with VirtualGL. 
+* --time=1:00:00  -> Set the default wallclock time to 1 hour (the maximum is 24 hours).
+* Please check 'salloc --help' and 'srun --help' for more details.
+
+
+=== 3. Tunnel VNC traffic to workstation
+Now you have to open an SSH tunnel from your workstation to node on which your VNC server is running. \\
+The steps to be done depend strongly on your operating system and your setup.
+
+'''Linux:'''\\
+If your operating system is Linux use for interactive nodes (NODE is most likely jurecavis01... or jurecavis02...):
+{{{ #!ShellExample
+ssh -N -L <5900+DISPLAY>:<NODE>:<5900+DISPLAY> <USERID>@<NODE>.fz-juelich.de
+# example: ssh -N -L 5907:jurecavis01:5907 jjuser@jurecavis01.fz-juelich.de
+}}}
+
+and for dedicated nodes:
+{{{ #!ShellExample
+ssh -N -L <5900+DISPLAY>:<NODE>:<5900+DISPLAY> <USERID>@jureca.fz-juelich.de
+# example: ssh -N -L 5902:jrc1327:5902 jjuser@jureca.fz-juelich.de
+}}}
+
+
+
+'''Windows:'''\\
+In case your operating system is Windows, the setup of the tunnel depends on your ssh client. \\
+Here a short overview on how-to setup a tunnel with [http://www.putty.org/ PuTTY] is given.
+
+It is assumed that PuTTY is already configured in a way that a general ssh connection to JURECA is possible. \\
+That means that host name, user name and the private ssh key (using PuTTY's Pageant) are correctly set.
+
+To establish the ssh tunnel, enter the "SSH-->tunnels" tab in the PuTTY configuration window. \\
+You have to enter the source port (eg. <5900+DISPLAY> = 5902 if DISPLAY=2) and the destination (in this case localhost:<5900+DISPLAY>) and than press add. \\
+After pressing add, the tunnel should appear in the list of forwarded ports and you can establish the tunnel by pressing the open button:
+
+[[Image(PuTTY-add-tunnel.png, 320px)]]
+[[Image(PuTTY-tunnel-added.png, 320px)]]
+
+
+=== 4. Start a VNC viewer and connect
+If you are using Linux, a VNC viewer typically is already part of the distribution or can be installed from a repository. \\ For Windows, a VNC viewer can be downloaded for example [http://sourceforge.net/projects/turbovnc/files/ here].
+
+Start your local VNC client and connect to localhost:<DISPLAY>, e.g.:
+{{{ #!ShellExample
+vncviewer localhost:2
+}}}
+After typing in your VNC password (defined in step 1), you will have access to the remote graphical desktop running on the visualization node of JURECA.