Each Metropolis user has access to three disk areas that can be used for processing data. Each area, is intended to be used as follows*:
|Directory||Intended use||Storage time||Backup||Default quota/user|
|$HOME (a.k.a /home/$USER)||Initialization scripts, source codes, small data files, long term data. Not for running programs or research data.||Permanent||Yes||25 GB|
|$TMPDIR (a.k.a /tmp on each node)||Limited, temporary storage (filesystem in RAM)||Temporary||No||None|
|/scratch||For running programs or processing research data.||Permanent||No||100 GB|
The directories listed in the table above can be accessed through the Linux command line. Apart from /tmp, home and /scratch filesystems are built on top of redundant arrays to provide maximum reliability. The /scratch filesystem relies on a parallel storage with Lustre and provides the best performance for handling large data sets or large number of data files.