How can a job locate scratch space?
The posix standard defines an environment variable TMPDIR which should point to a suitable scratch area – there is no definition for how large this should be but it’s likely to be at least several Gb, typically on a disk local to the Worker Node. However, there is no guarantee that this variable will be set at every site. If it is not set the job should write into whatever working directory is defined at the start of execution. /tmp should not be used except for small files. No area, including the home directory of the account under which the job runs, should be assumed to be persistent between jobs; for persistent files use a Storage Element.
