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All NERSC users should back up important files to HPSS on a regular basis. Ultimately, it is your responsibility to protect yourself from data loss.


Global homes and Community use a snapshot capability to provide users a seven-day history of their directories. Every directory and sub-directory in global homes contains a ".snapshots" entry.

  • .snapshots is invisible to ls, ls -a, find and similar commands
  • Contents are visible through ls -F .snapshots
  • Can be browsed normally after cd .snapshots
  • Files cannot be created, deleted or edited in snapshots
  • Files can only be copied out of a snapshot


Global homes are backed up to HPSS on a regular basis. If you require a restoration of lost data that cannot be accomplished via the snapshots capability, please contact NERSC Consulting with pathnames and timestamps of the missing data. Such restore requests may take a few days to complete.



See Filesystem Quotas and Purging for detailed information about inode, space quotas, and file system purge policies.


$SCRATCH directories are not backed up