DaVinci File Systems

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

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

Your $HOME Directory

When you login to DaVinci, you are put into your home directory by default.

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. In general 'hsi archive.nersc.gov' is the most efficient method for storing and retrieving files to/from the HPSS system. Users with large numbers of small files may benefit from using the htar tool.

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 file space quota for individual home directories is modest - 15 GBytes of file space per user. There is no quota for the number of inodes (each file or directory that you own counts as one inode). The myquota command (with no options) will give you information on the limits in your $HOME directory. For example:

e/elvis> myquota
Displaying quota usage for group elvis:
            ---------- Space (GB) ----------  ------------ Inode -------------
FileSystem   Usage    Quota   InDoubt  Grace   Usage    Quota   InDoubt  Grace
----------  -------  -------  -------  -----  -------  -------  -------  -----
homes             2       14        -      -     5426        -        -      -
scratch           3        -        -      -     8316        -        -      -

The output shows the limit on file space and inodes, as well as the current usage (note that on DaVinci, quotas are associated with a user's personal file group, not with their login name). If you reach the "quota" value, you will not be able to save anything else to disk in that file system.

Your $SCRATCH Directory

$SCRATCH

The environment variable $SCRATCH refers to your scratch directory, which is part of the /scratch file system that provides 21 TBytes of space shared by all users. The contents of $SCRATCH may be deleted at any time if /scratch becomes near capacity. In general, files in $SCRATCH will persist for at least 7 days, but users are "taking chances" by using $SCRATCH to store files longer than 7 days, and should not rely on it to be "semi-permanent" file storage space.

There are currently no space or inode quotas for users on the /scratch file system.

/tmp

The /tmp file system is actually part of the root file system, and is not very large. Users are urged not to use /tmp. If /tmp is filled, processes will likely crash, and may take the node down as well. In most circumstances $SCRATCH will give better performance than /tmp.

Users migrating software and scripts to DaVinci 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