Compute clusters may have different environments on the front-end nodes, the service nodes and the compute nodes. It does not necessarily hold that the same file systems exist on all nodes or are mounted in the same location.

Freja produces temporary files during sampling. These can become quite large for long executions, although the growth rate tapers off during the run. To impose a minimum disturbance on the network and I/O system, you need to ensure that these temporary files are stored as close to the node as possible.

To control where temporary files are stored, you should either point one of the environment variables THREADSPOTTER_TMPDIR or TMPDIR to a suitable directory or provide the directory name in a parameter to the sample command. The default is the system temporary directory, typically /tmp, which may not be suitable. On some systems this directory is in a memory mapped file system with limited capacity.