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Logging in to Cori

Interactive Access

Log in to Cori using SSH (Secure Shell) with the following command from any UNIX, Mac OS X, Linux, FreeBSD, etc. command shell or terminal: 

ssh -l username cori.nersc.gov

There are several SSH-capable clients available for Windows, Mac, and UNIX/Linux machines. NERSC does not support or recommend any particular client. Cori only accepts RSA SSH keys security reasons.  

When you log into Cori, you will be randomly placed on one of 23 login nodes, which will all appear to you as "cori.nersc.gov."  (The "load balancer does have some memory, so your consecutive logins are likely to land on the same node.)  The login nodes are where you compile codes, submit jobs, and view data.  The login nodes on Cori are "external," meaning they are not directly connected to Cori internal high-speed "Aries" network. Because the login nodes are external you may be able to log in and work with data and files when the main system is undergoing maintenance. 

Since the login nodes are a shared resource among you and many NERSC users, please do not execute long-running applications on the login nodes.  Instead, use the batch system to direct your compute-intensive jobs to the compute nodes.

Accelerated X11 Performance

Some interactive tools, like debuggers, use the X-Windows protocol to display their graphical user interface. This protocol is highly sensitive to network latency and often performs poorly over the large area network. NERSC has installed a software package that optimizes X-Windows communications, called NX.  NERSC recommends NX for those having X11 performance issues when running X applications at NERSC. See  Connecting to NERSC  for more information.

Data Transfer 

SSH distributions on Linux and many other platforms provide a data transfer tool called scp, which uses the same authentication mechanisms as SSH. Globus and other tools can also be used to transfer files to and from Cori. See Transferring Data.