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It is the responsibility of every user to organize and maintain software and data critical to their science. Managing your data requires understanding NERSC's storage systems.


NERSC provides several filesystems, and to make efficient use of NERSC computing facilities, it's critical to have an understanding of the strengths and limitations of each filesystem.


JAMO is JGI's in-house-built hierarchical file system, which has functional ties into NERSC's filesystems and tape archive. JAMO is not maintained by NERSC. To learn more about JAMO, click here.

All NERSC filesystems have per-user size limitations, or quotas. To check your filesystem usage use the myquota command from any login node, check the Data Dashboard on or log into the NERSC Information Management (NIM) website and click on the "Account Usage" tab.


Your home directory is mounted across all NERSC systems. You should refer to this home directory as $HOME wherever possible, and you should not change the environment variable $HOME.

Each user's $HOME directory has a quota of 40GB and 1M inodes. In most cases, $HOME quotas cannot be increased, and users should make use of other filesystems for storage of large volumes of data and for computation.


As a global filesystem, $HOME is shared by all users, and is not configured for performance. Do not write scripts or run software in a way that will cause high bandwidth I/O to $HOME. High volumes of reads and writes can cause congestion on the filesystem metadata servers, and can slow NERSC systems significantly for all users. Large I/O operations should always be directed to scratch filesystems.


projectb is a 2.7PB GPFS based file system dedicated to the JGI's active projects. There are two distinct user spaces in the projectb filesystem: projectb/sandbox and projectb/scratch. The projectb filesystem is available on most NERSC systems.

projectb Scratch projectb Sandbox
Location /global/projectb/scratch/$username /global/projectb/sandbox/$program
Quota 20TB, 5M inodes by default; 40TB upon request Defined by agreement with JGI Management
Backups Not backed up Not backed up
File Purging Files not accessed for 90 days are automatically deleted Files are not automatically purged

projectb "Scratch" and "Sandbox" space is intended for staging and running JGI calculations on the NERSC systems, including Denovo, Cori, and Edison. On Denovo, the projectb scratch space is the recommended filesystem for performing file IO during all your calculations, and the environment variable $BSCRATCH points to the user's projectb scratch space. If you have access to the Genepool resources, you should have space on projectb scratch. If you don't, please file a Consulting ticket.

The Sandbox areas were allocated by program. If you have questions about your program's space, please see your group lead. New Sandbox space must be allocated with JGI management approval.

DnA (Data n' Archive)

DnA is a 1PB GPFS based file system for the JGI's archive, shared databases and project directories.

DnA Projects DnA Shared DnA DM Archive
Location /global/dna/projectdirs/ /global/dna/shared /global/dna/dm_archive
Quota 5TB default Defined by agreement with the JGI Management Defined by agreement with the JGI Management
Backups Daily, only for projectdirs with quota <= 5TB Backed up by JAMO Backed up by JAMO
Files are not automatically purged Files are not automatically purged Purge policy set by users of the JAMO system Files are not automatically purged

The intention of the DnA "Project" and "Shared" space is to be a place for data that is needed by multiple people collaborating on a project to allow for easy access for data sharing. The "Project" space is owned and managed by the JGI. The "Shared" space is a collaborative effort between the JGI and NERSC.

If you would like a project directory, please use the Project Directory Request Form.

The "DM Archive" is a data repository maintained by the JAMO system. Files are stored here during migration using the JAMO system. The files can remain in this space for as long as the user specifies. Any file that is in the "DM Archive" has also been placed in the HPSS tape archive. This section of the file system is owned by the JGI data management team.


Each user has a "scratch" directory. Scratch directories are NOT backed up and files are purged if they have not been accessed for 90 days. Access your scratch directory with the environment variable "$SCRATCH" for example:


Scratch environment variables:

Environment Variable Value NERSC Systems
$SCRATCH Best-connected file system All NERSC computational systems
$BSCRATCH /global/projectb/scratch/$username Denovo only
$CSCRATCH /global/cscratch[1,2,3]/sd/$username Cori and Edison

$BSCRATCH points to your projectb scratch space if you have a BSCRATCH allocation. $SCRATCH will always point to the best-connected scratch space available for the NERSC machine you are accessing. For example, on Denovo $SCRATCH will point to $BSCRATCH, whereas on Cori $SCRATCH will point to $CSCRATCH.

The intention of scratch space is for staging, running, and completing your calculations on NERSC systems. Thus these filesystems are designed to allow wide-scale file reading and writing from many compute nodes. The scratch filesystems are not intended for long-term file storage or archival, and thus data is not backed-up, and files not accessed for 90 days will be automatically purged.

Policies for $SCRATCH are described at NERSC Data Management Policy.

Other file systems

Other file systems used by JGI may also be mounted on NERSC systems:

  • SeqFS - file system used exclusively by the Illumina sequencers, SDM and Instrumentation groups at the JGI.
  • /usr/common - is a file system where NERSC staff build software for user applications. This is the principal site for the modular software installations.
  • /global/project - is a GPFS based file system that is accessible on almost all of NERSC's other compute systems used by all the other NERSC users. The projectdir portion of projectb should be favored by JGI users instead of /global/project.