Ifarm graphic mode
For any question, email Zhiwen Zhao email@example.com
Usually we are running code on ifarm without caring about graphic because it's used for a test ground for farm job anyway.
Sometimes we do want to test a code's graphic feature. For example, it's a common system we all have access and can be used for debug.
Sometime you also want to connect to other machines at jlab for graphic
connect to ifarm at jlab by vnc
Xwindow forwarding (not recommended)
It is simply use Xwindow forwarding by ssh into ifarm and run the code.
Xwindow graphic is always rendered in your local machine. This is not only very slow if your machines is outside of jlab network, but also can have different results for different people because their local machines are different. Sometimes, it can even cause crash of your local machine if your code is not nice and your local machine is very different from ifarm.
ssh -XY your_lab_username@ifarm (login with Xwindow forwarding enabled for linux and Mac) xclock & (test if Xwindow forwarding works)
If you local machine is windows, you need to have a Xwindow server like Xming-mesa running. You also you need to enable Xwindows forwarding in putty option to use ssh
If you local machine is Mac, you need to have a Xwindow server installed and enabled
The better way to do it is through a vnc server inside ifarm. This way the code won't crash because it runs within the same environment where it is compiled and everyone will see same result. Here is how to do it
ifarm is an alias to a few machines and would cause confusion, you need to use one fixed machine like ifarm1901 as example below.
start vnc server
Warning: running vncserver on ifarm is only for very quick testing. it can be killed because limited process from one user on ifarm and remember to kill it after use to release resource
First you need to start a vncserver on ifarm1901
ssh -XY firstname.lastname@example.org (login with Xwindow forwarding enabled) mkdir .vnc edit .vnc/xstartup with lines below #!/bin/sh xsetroot -solid grey vncconfig -iconic & xterm -geometry 160x50+10+10 -ls -title "$VNCDESKTOP Desktop" & metacity & chmod 755 .vnc/xstartup vncserver (start vnc server) or vncserver -bs (start vnc server this way if somehow quitting program root will kill vncserver) (give a password if running it first time, or run vncpasswd to enter password note the vnc server port number output on screen make sure to kill the server after you using it to free resource on ifarm, otherwise it will keep running even after you log out!) vncserver -kill :port (replace port with correct vnc server port number, note the space before colons)
run vnc viewer
Next you need to connect to the vnc server on ifarm1901 by a vnc viwer
The simple way is to use vncviewer on ifarm to test see if your vncserver runs ok. It's slow if your machine is not at jlab network
ssh -XY your_lab_username@ifarm1901 (login with Xwindow forwarding enabled) vncviewer localhost:port (replace port with correct vnc server port number)
The best way is run vncviewer on your machine anywhere through ssh tunneling
built ssh tunnel as follows with correct port number of vnc server if your linux or mac machine is at jlab, run "ssh -X -N -g -L 5999:localhost:port email@example.com" if your linux or mac machine is outside jlab, run "ssh -X -N -g -L 5922:ifarm1901:22 firstname.lastname@example.org" and another "ssh -X -N -g -L 5999:localhost:port your_lab_username@localhost -p 5922" if you windows machine is at jlab, use putty to connect to ifarm1901.jlab.org:22 by add Connection->SSH->Tunnels with source port 5999 and destination localhost:port" if you windows machine is outside jlab, use putty to connect to login.jlab.org by add Connection->SSH->Tunnels with source port 5922 and destination ifarm1901:22" and another putty to connect to localhost:5922 by add Connection->SSH->Tunnels with source port 5999 and destination localhost:port" get a good vncviewer then run vncviewer and connect to localhost:99 choose lower graphic quality for better speed and scale to window size in option for best use
connect to any machine's main desktop at jlab by x11vnc
"vncserver" create a new X server independent of the main X server.
But you can connect to main desktop by "x11vnc" and ssh tunneling as if you are sitting in front of it
at the remote host, if x11vnc is not installed, run "yum install x11vnc" as root to install it. If you have ssh key on login server or your remote host, disable it temporarily by renaming .ssh/authorized_keys. as an example, start x11vnc in the machine called lily.jlab.org as follows run "x11vnc -localhost -auth guess -display :0 -repeat -shared -forever -rfbport 5900 &" It's preferred to run it as root so that you can do vnc even before login after computer boots. If you don't have root access, just run it as regular user, but sometime it fails after computer reboot because xwindow auth can't be established. then the fix is usually that you have to login in front of your computer first
at your local machine, as an example,connect to host lily from your machine outside jlab as follows For linux or mac, run in a terminal "ssh -X -N -g -L 5922:lily:22 email@example.com", then run in another terminal "ssh -X -N -g -L 5999:localhost:5900 your_lab_username@localhost -p 5922" (both terminals will just stay there without allowing you to input anything and you keep both alive.) For windows, use putty to connect to login.jlab.org by add Connection->SSH->Tunnels with source port 5922 and destination lily:22" and another putty to connect to localhost:5922 by add Connection->SSH->Tunnels with source port 5999 and destination localhost:5900" The first ssh tunneling connect your localhost:5922 to lily:22 through login:22 and the second ssh tunneling connect your localhost:5900 to lily:5900 through localhost5922 which is actually lily:22
at your local machine, get vncviewer then run vncviewer and connect to localhost:99 choose lower graphic quality for better speed and scale to window size in option for best use