Login Nodes

Login Node Quick Facts

• When you ssh to hopper.nersc.gov, you are connecting to a "login node."
• Login nodes are used to edit files, compile codes, and submit job scripts to the batch system to run on the  "compute nodes."
• Hopper has 12 login nodes (this is largely transparent to users).
• 4 quad-core AMD 2.4 GHz Opteron 8378 processers (16  cores total) each on 8 of the login nodes.
• 4 8-core AMD 2.0 GHz Opteron 6128 processors (32 cores total) each on 4 of the login nodes.
• Each login node has 128 GB of memory.
• You will be connected to the login node with the fewest number of active connections.
• The login nodes are external to the main Cray XE6 system so you can log in and work with data and submit jobs when the compute portion of Hopper is undergoing maintenance.

Process Limits and Appropriate Use of Login Nodes

Hopper does not  have process limits, but please be considerate of other users and do not attempt to run compute-intensive or large-memory jobs on the login nodes.  CPU- and memory-intensive applications should be run on the compute nodes and submitted through the batch system.   NERSC  reserves the right to kill processes on the login nodes if responsiveness is being impacted.