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Warning!

Puhti and Mahti are being decommissioned in stages, and their storage areas will become fully unavailable from 15 October 2026. Clean up unnecessary files and move any data you need to keep by 31 August 2026. See the Roihu data migration guide for instructions on transferring your data to Roihu.

Puhti scratch is very full: keep only active data there and move or delete everything else. No new Puhti scratch quota will be granted.

Where should I put my data?

The Roihu supercomputer uses a parallel file system called Lustre. Data on Lustre is accessible from all nodes of a system, and is thus the best place to store the data that you need for computations. Please note that you can not directly access data on Roihu from Mahti or vice versa, i.e. they have their own Lustre file systems. You can, however, move data between Roihu and Mahti using tools such as rsync.

See the detailed data migration guide from Mahti and Puhti to Roihu.

More specifically, Roihu has three main disk areas: home, projappl and scratch. The home directory (accessible using the $HOME environment variable) is the only user-specific directory. The other directories scratch and projappl are project-based and shared by all members of a project. You can access them at /scratch/<project> and /projappl/<project>, respectively, where <project> should be replaced by the actual ID of your CSC project (see How to find information about my projects). This also means that if you are a member of several projects, you also have access to multiple scratch and projappl directories. You will, however, only have one home directory.

What do you need? Recommended location
Temporary input, output and intermediate data for one computational project /scratch/<project-id> (Roihu)
Software, scripts and small reference files shared within one computational project /projappl/<project-id> (Roihu)
One or a few actively used dataset(s) that several Roihu computational projects need to read /dataset/<dataset-project-id> (Roihu)
Backups, inactive data or longer-term object storage Allas or LUMI-O
Published or preserved research data An appropriate research data repository or preservation service

The /dataset directory is not included in a normal computational project in Roihu. To use it, apply for a separate Roihu dataset project.

When logging in to Roihu, you should change to your project's scratch directory because the home directory is not intended for storing data that is required for analysis or computing. Its purpose is to store configuration files and other minor user-specific data (default quota 15 GB). A directory exceeding its capacity causes various problems (see Disk quota exceeded). The scratch disk is the main disk area to store your active research data (default quota 250 GB on Roihu), while projappl is intended, for example, for project-wide installations of custom software and libraries (default quota 15 GB on Roihu). See more information about the disk areas.

CSC does not back up your data!

None of the disk areas are automatically backed up by CSC. This means that data accidentally deleted by the user cannot be recovered in any way. Also keep in mind that files on the scratch disk that have not been used in 180 days will be automatically deleted.

To avoid unintended data loss, please move files that are not in active use away from scratch and remember to take regular backups of your important data to, for example, Allas or your own organization's storage systems.

One of the main use cases of Allas is to store data that is not in active on the CSC supercomputers. Before working on the data on an HPC system, copy it from Allas to the supercomputer (stage in). When the data is no longer actively used it can be staged out, i.e. uploaded back to Allas.

Read more about common use cases of Allas and see the example of hosting a dataset.