Jacquard File Systems

• Your home directory
• Your scratch directory
• The project directory
• Quota Summary

All user-accessible file storage on Jacquard is provided by the General Parallel File System (GPFS), which provides a large amount of fast data storage and is available from all nodes. User home directories and a large amount of scratch space are both provided by GPFS. To move files between Jacquard and other systems, use scp. To move files bewteen Jacquard and NERSC's archival storage system (archive.nersc.gov), use ftp/pftp, hsi, or htar.

Your $HOME Directory

When you login to Jacquard, you are put into your home directory by default. Home directories are available from all nodes.

Your home directory can (and should) always be referred to by the environment variable $HOME. The absolute path to your home directory (e.g., /u4/elvis/) may change, but the value of $HOME will always be correct.

Home directories are not backed up (except for file system recovery purposes). Please save all your important files to HPSS on a regular basis.

For security reasons, you should never allow "world write" access to your $HOME directory or your $HOME/.ssh directory. NERSC scans for such security weakness, and, if detected, will change the permissions on your directories.

In your home directory are various login control files (e.g. ".login", ".cshrc", ".profile"). These are symbolic links to common files that contain definitions shared by all users. Please do not remove the links in your home directory. If you wish to customize your login behavior, please place all your personal customizations in extension files with names such as .login.ext, .cshrc.ext, and .profile.ext.

The home directories are part of the General Parallel File System (GPFS). The file space quota for individual GPFS accounts is modest - 5 GBytes of file space per user. Each user has a separate quota for the number of inodes. Each file or directory that you own counts as one inode against your quota. The myquota command (with no options) will give you information on the limits in your $HOME directory. For example:

The output shows the limit on file space (Block Quota) and inodes (Inode Quota), as well as the current usage. If you reach the "Quota" value, you will not be able to save anything else to disk in that file system. In this example the home directory is in /u2. The "InDoubt" columns tells you that the reported "Usage" may be off by that amount. This occurs because GPFS does not update this information immediately upon change.

Your $SCRATCH Directory

$SCRATCH

The environment variable $SCRATCH refers to a directory in GPFS which provides 21 TBytes of scratch space that is shared by all users. $SCRATCH is available from all nodes. The contents of $SCRATCH may be deleted at any time after the job finishes if the system's disks near capacity. In general, files in $SCRATCH will persist for at least 7 days, but users are "taking chances" by using $SCRATCH to store after the job finishes and should not rely on it to be "semi-permanent" file storage space.

There is a (large) quota for users on the /scratch file system. Use the myquota command to check your usage and quota.

/tmp

The /tmp file system is local to each node and is not very large. Users are urged not to use /tmp. If /tmp is filled, your job will likely crash and may take the node with it. In most circumstances the GPFS file system ($SCRATCH) will give better performance than /tmp.

Users migrating software and scripts to Jacquard from other systems should be careful to check for assumptions about the use of /tmp, which is a common place to build software on some systems. All references to /tmp in user scripts, makefiles and codes should be changed to $SCRATCH.

The project Directory

Quota Summary

NERSC sometimes grants temporary quota increases for legitimate purposes. To apply for such an increase, or to request the creation of a collaborative project directory, please see Disk Quota Change Request Form.