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Working Filesystems

As soon as you have access to ZIH systems, you have to manage your data. Several filesystems are available. Each filesystem serves for special purpose according to their respective capacity, performance and permanence.

Filesystem Type Usable Directory Capacity Availability Remarks
Lustre /data/horse 20 PB global Only accessible via Workspaces. The(!) working directory to meet almost all demands
Lustre /data/walrus 20 PB global Only accessible via Workspaces. For moderately low bandwidth, low IOPS. Mounted read-only on compute nodes.
WEKAio /data/weasel 1 PB global (w/o Power) Coming 2024! For high IOPS
ext4 /tmp 95 GB node local Systems: tbd. Is cleaned up after the job automatically.

Recommendations for Filesystem Usage

To work as efficient as possible, consider the following points

  • Save source code etc. in /home or /projects/...
  • Store checkpoints and other temporary data in workspaces on horse
  • Compilation in /dev/shm or /tmp

Getting high I/O-bandwidth

  • Use many clients
  • Use many processes (writing in the same file at the same time is possible)
  • Use large I/O transfer blocks
  • Avoid reading many small files. Use data container e. g. ratarmount to bundle small files into one

Cheat Sheet for Debugging Filesystem Issues

Users can select from the following commands to get some idea about their data.

General

For the first view, you can use the command df.

marie@login$ df

Alternatively, you can use the command findmnt, which is also able to report space usage by adding the parameter -D:

marie@login$ findmnt -D

Optionally, you can use the parameter -t to specify the filesystem type or the parameter -o to alter the output.

Important

Do not use the du-command for this purpose. It is able to cause issues for other users, while reading data from the filesystem.