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Overview

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.

Work Directories

Filesystem Usable directory Capacity Availability Backup Remarks
Lustre /scratch/ 4 PB global No Only accessible via Workspaces. Not made for billions of files!
Lustre /lustre/ssd 40 TB global No Only accessible via Workspaces. For small I/O operations
BeeGFS /beegfs/global0 232 TB global No Only accessible via Workspaces. Fastest available filesystem, only for large parallel applications running with millions of small I/O operations
ext4 /tmp 95 GB local No 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 /scratch/ws/...
  • 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

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.