Key directories on M3

From the user's perspective, M3 has three key filesystems.

Directory	Name	Backed up?	What files to place here?
~	Home directory	Yes	Small personal configuration files, secret keys that you don't want anyone else reading, etc.
/projects/ab12	Project directory	Yes 1	All of your input data, your job scripts, and final output data. Basically anything that would be hard to regenerate.
/scratch2/ab12	Scratch directory	No	All of your intermediate/working data. If you can easily regenerate it, then it can probably go in /scratch2.
/tmp	temp directory local to each server	No	Temporary files that are not needed at the end of your program 2

Read further information about backups on M3.

Footnotes

1. We are currently changing how we backup /projects/. Please contact us if you want more information. ↩

2. Each server has its own local file system, with a small /tmp folder for temp files. But if you access a node via a Slurm job then /tmp is mapped to a faster and larger local file system. Any data placed in this Slurm-created /tmp file system is deleted at the end of the Slurm job. On login and dtn nodes users must be careful not to fill the small /tmp. It is also global, i.e. all users can view and write to it. If your data is sensitive, please check that any files created have the correct Unix file protections. The Bash environment variable TEMPDIR can often be used to redirect temp files to another larger file system. Please contact us if you want more information. ↩