Login Server (Access node)
Via the login server the compute nodes of the cluster are accessible. The login server is designed to be used interactively. To work with bwGRiD Cluster Heidelberg you log-in on the login server first. From here you can submit batch jobs or connect to one of the compute nodes to work interactively on the compute nodes.
Interactive Access to the Login Server from a Linux/Unix Computer
For security reasons only Secure Shell (SSH) should be used. From a Linux/Unix computer a SSH connection can be established by the following command.
ssh bwgrid.uni-heidelberg.de
If your user names on both sides of the SSH connection are different, declare your cluster user name. A cluster user pat can type-in for example
Many application programs offer a graphical user interface (GUI). To work with a GUI your SSH connection must be X11 capable. You can manage this by setting one of the options -X, -Y or -XY. Example:
ssh -Y bwgrid.uni-heidelberg.de
RSA key fingerprint of the login server is
2c:ba:b8:7b:78:d4:e8:c8:74:7a:8b:82:80:34:e3:ee
Interactive Access to the Login Server from a Windows Computer
For security reasons only Secure Shell (SSH) should be used. The login server has got the alias name
bwgrid.uni-heidelberg.de
This name you can fill-in as destination host in the connect form of your SSH software. A SSH client is not part of the Windows system software. Some SSH programs are offered for free and can be downloaded, e.g. PuTTY and Tera Term. The PuTTY executable putty.exe is able to run under Windows without installation, download is sufficient.
To work with a graphical user interface your SSH connection must be X11 capable. A software which can manage this and is free for non-profit use is Xming. The download contains PuTTY too.
Xming can be configured in the following way if PuTTY shall be used as SSH client.
The two remaining pages of the configuration dialog can be overtaken without change. After clicking the "Finish" button PuTTY will be launched automatically and you can start your session.
File Transfer
For security reasons only Secure Copy (SCP) is permitted for file transfer via network. By using SCP you can tranfer files from your local machine to the login server and in the opposite direction.
IMPORTANT: Always use the most recent version of the SSH and SCP software!
For example, if you want to copy the file input from your local Linux/Unix computer to the login server, you may type
scp input bwgrid.uni-heidelberg.de:
Example for transfer in the opposite direction:
scp bwgrid.uni-heidelberg.de:*.out .
All files with extension out will be copied from your home directory on the login server to the current directory of your local machine. You can specify a source and/or a target directory, too. Example:
scp bwgrid.uni-heidelberg.de:source/*.out target/
A different cluster user name you can send on before, as mentioned above. Example:
Users with Windows frontend are dependent on Secure Copy, too. A free SCP client is WinSCP.
Operating System
The operating system on the login server is the same as on the compute nodes, Scientific Linux 5.5. Compute nodes and login server use different kernel versions. You can inquire the present kernel version with the command
uname -r
