Skip to main content
  1. FAQ
  2. Personal Account Questions
  3. Filesystem Backups in the CS Department

Filesystem Backups in the CS Department

Retention Policy for Junkfood Home Directories and Web Directories

      An hourly copy is kept for 5 days.
A daily copy is kept for 2 weeks.
A weekly copy is kept for 2 months.
A monthly copy is kept for 2 years.

Recovering Files

If you need to restore a file from your Junkfood Home Directory or your Web Directory (www.cs.umd.edu/~user), follow the simple steps below.

To restore a file from “junkfood home”:

  1. Log in to a junkfood system.

  2. Go to the backup directory: cd /fs/userdata/.zfs/snapshot

  3. Snapshot directories are named by date and time in UTC. Go to, for example: cd zrepl_20260101_170000_000/$USER/

  4. Copy the desired file back to the desired junkfood home directory:

    cp deletedFile ~/folderName

To restore a file from www.cs.umd.edu/~userName:

  1. Log in to a junkfood system.

  2. cd /fs/wwwusers/.zfs/snapshot

  3. Snapshot directories are named by date and time in UTC. Go to, for example: cd zrepl_20260101_170000_000/$USER/

  4. Copy the desired file back to your web directory:

    cp deletedFile /fs/wwwusers/$USER/folderName

Please note that /tmp directories on the junkfood machines are not backed up. Any data that was written there will not be retrievable when the /tmp is cleared by a system reboot.

If you are unable to find the desired file or you would like to restore a file from a system not mentioned here, please email IT staff by staff at cs.umd.edu. Include the information that you last accessed successfully and recover to where.

To restore a file from www.cs.umd.edu/class/cmscXXX:

  1. Log in to a junkfood system.

  2. cd /fs/www/.zfs/snapshot

  3. Snapshot directories are named by date and time in UTC. Go to, for example: cd zrepl_20260101_170000_000/class/cmscXXX

  4. Copy the desired file back to a directory:

    cp deletedFile /tmp

Please note that /tmp directories on the junkfood machines are not backed up. Any data that was written there will not be retrievable when the /tmp is cleared by a system reboot.

If you are unable to find the desired file or you would like to restore a file from a system not mentioned here, please contact IT staff by completing this form.

To restore a file from a project site (/fs/www/projects, e.g. projects.cs.umd.edu):

  1. Log in to a junkfood system, or any workstation where /fs/www/projects is available.

  2. Go to the snapshot directory: cd /fs/www/projects/.snap

  3. Snapshot directories here are named differently than the ones above — by date and time in UTC, but formatted like scheduled-2026-07-17-16_00_00_UTC. Go to, for example: cd scheduled-2026-07-17-16_00_00_UTC/yourProjectDirectory/

  4. Copy the desired file back to your project directory:

    cp deletedFile /fs/www/projects/yourProjectDirectory/

Snapshots here follow the same retention as the policy above (hourly for 5 days, daily for 2 weeks, weekly for 2 months, monthly for 2 years).

If you are unable to find the desired file, please email IT staff by staff at cs.umd.edu.