How to ... Store Files

NERSC provides a number of types of file storage space for users:

• A $HOME directory for permanent file storage for each user on each platform.
• A $SCRATCH dirctory for temporary file storage for each user on each platform.
• A "project" directory in the NERSC Global Filesytem, which is mounted from all platforms. Project directories are for permanently storing files to be shared by a group. These directories are available upon request.
• an HPSS mass storage system for long-term file storage of large datasets, available via HPSS softare utiltities from the compute platforms.

Disk Directories

When you log into a NERSC computer interactively, you are in your home directory by default ($HOME). Directories consist of disk space where you can keep files that you want to be able to retain permanently (however, data stored in your home directory is backed up for disaster recovery purposes only; users should back up their own files as needed). Quotas are in effect that limit the amount of data that can be saved there. The myquota command will show you your usage and limits.

There is also a large, temporary disk space that you can use to store files while you run programs from batch scripts. referenced by $SCRATCH.

Never explicitly use /tmp on any NERSC system; this filesystem is very small and reserved for system use.

Archival Storage

You may also store your files on the NERSC HPSS mass storage system. The mass storage (or archival storage) facilities are used to permanently save large amounts of data that exceed the quota on your home directory. It will take from seconds to hours to retrieve data from the mass storage systems, depending on a number of factors, including the file size and the amount of time it has been dormant in storage.

The primary user interface to transfer files to and from HPSS is known as hsi.

See HPSS for more information on how to use the archival storage facilities.