Franklin has 10 login nodes directly connected to the compute nodes. Another login node, named "Freedom," is connected "externally."
Login nodes are used to edit files, compile codes, and submit job scripts to the batch system to run on the "compute nodes."
Internal Login Nodes
- When you ssh to franklin.nersc.gov, you are connecting to an internal "login node."
- Franklin has 10 internal login nodes (this is largely transparent to users).
- Each node has 1 dual-core AMD 2.6 GHz processers (2 cores total)
- Each node has 8 GB of memory.
- You will be connected to the login node with the fewest number of active connections.
- The internal login nodes are integrated into the main Cray XT4 system. You cannot log in and work with data and submit jobs when the compute portion of Franklin is undergoing maintenance.
- The default per-login process limits are 60 minutes of CPU and 2 GB of memory.
External Login Node
Freedom is a Franklin login node that is more powerful (more CPU and memory, with physical disk) that is connected externally to the main Franklin system. Freedom is suitable for running memory-intensive utilities and serial programs like IDL, DDT, parallel make, hsi, and htar.
- When you ssh to freedom.nersc.gov, you are connecting to the "external" login node named "Freedom".
- You can also log in and work with data when the compute portion of Franklin is undergoing maintenance.
- Freedom has 4 quad-core AMD 2.4 GHz processers (16 cores total)
- Freedom has 64 GB of memory.
- When Franklin is down, its scratch file systems are not available from Freedom and you may receive an error message: "No such file or directory" if you try to access /scratch.
- Your home directory and /project directory are accessible from Freedom even when Franklin is down.
- When Franklin is down, batch commands (qstat, qsub, etc.) from Freedom will either hang or receive an error message: "cannot connect to server".
- When Franklin is down, you should create the directory /tmp/$USER and set the environment variable TMPDIR to the value: /tmp/$USER .
- The "myquota" command does not display information about the Franklin scratch file systems.
- New Franklin users must ssh to franklin.nersc.gov at least once in before using Freedom.
- Under the PrgEnv-cray environment, you must set TMPDIR to /tmp for the compilers to work.
- The default per-login process limits are unlimited CPU time and 4 GB of memory.
Appropriate Use of Login Nodes
The login nodes are shared resources. 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.