You should back-up your Mongo DB data frequently. The Mongo DB NERSC offers is not backed-up automatically. It's important to run regular backups during the course of your research. For Mongo DB you can:
Get a free education license for Studio 3T, right click your database, and click export or,
use the “mongodump” command line tool, tutorials available online — it’s a one line command
module load mongodb; mongodump --host=<host e.g. mongo01.nersc.gov> --port=20717 --username=<username> --password="<password>" --db="<db_name>" --authenticationDatabase="<db_name (same as --db flag)>" --out="<path to directory>"
NERSC Cori, BRC Savio, LRC Lawrencium
You should back-up your "scratch" directory data frequently.
Each cluster has different methods of deleting old data on your scratch directory: