This page contains some additional information about the file system that did not fit anywhere else. It is still adviced to consider the following topics carefully.

Table of Contents

• Visibility of Filesystem
• Backup Exclusion
• Snapshots
• $TMP
• Broken Files on HPCWORK

Each user directory is only mounted when a process actually accesses it. Therefore, you might not see a specific user directory in a listing of /home, /work or /hpcwork (which can be confusing, especially if you are using a graphical file manager). This does not mean that a user directory does not exist, but that you might have to type the path to a user directory explicitly to actually get there. Any action that causes an access to your directory will mount it and thereby make it visible. This can be done by changing into the directory in a terminal or typing the full path of your directory in the address bar of your file manager.

The following files and directories are currently excluded from the backup in $HOME:

• Complete sub-directories: 
  • .NOBACKUP
  • ~/.cache
  • ~/.comsol/*/configuration
  • ~/.Trash*
  • ~/.local/share/Trash*
• File patterns:
  • core.*.rz.RWTH-Aachen.DE.[1-9]*.[1-9]*
  • core.*.hpc.itc.rwth-aachen.de.[1-9]*.[1-9]*

Snapshots reflect the state of a file system at previous points in time. By changing to a snapshot directory, ($HOME_SNAPSHOT or $WORK_SNAPSHOT), you can access previous versions of your files. The files within the snapshots are read-only, they can not be altered or deleted. Please note that the snapshots creation policy is subject to change. If space gets short, we may decide to create less snapshots, delete existing snapshots or omit them completely. Snapshots are not an alternative to a backup. If a file system gets damaged, all snapshots are lost, too.

In case you are using a sinlge node exclusively and would like to use the local SSD, BeeOND can cause some unneccessary overhead. In this case you can directly access the SSD via the path stored in $TMP.

We do not reccomend using the local SSD storage on shared nodes, as there are no restrictions on how much space each user can occupy. It is therefore unpredictable if storage space on the local SSD is available.

In your $HPCWORK directory you may sometimes encounter files for which the command ls -l reports an error "No such file or directory" and displays something like

-????????? ? ?        ?               ?            ? FILENAME

The reason is usually that parts of the file are lost, for example due to a crash of one of the HPCWORK file servers. Since there is no backup of $HPCWORK, we are not able to restore the content of such files. You can try to recover those parts of the file that are still readable with the command

dd_rescue -e 10240 -b 1M -B 1M <BROKEN_FILE> <RECOVERED_FILE>

In order to remove a broken file you might have to use the following command - rm will usually not work:

unlink <BROKEN_FILE>