How to create a CÉCI Common Storage project

The goal of the CÉCI Common Storage is to provide a filesystem accessible from all login and compute nodes of all CÉCI clusters. The common storage is synchronous; files and their content are immediately visible on all clusters.

Common Storage projects are created upon request by a Principal Investigator holding a permanent position at one of the five member universities, through this web page.

After submitting your request, you will receive an email with a link to a form for creating your project. The process is similar to that used for requesting Tier-1 projects. An overview of the process was presented during the CÉCI User Day 2025 and is available here.

Filling the form

• In the Project Type menu, select Common_Storage. Selecting anything else will create a Tier-1 project instead.
• Provide a title and an acronym that will uniquely identify your project. You will need to share this acronym with colleagues you wish to add to the project.
• Keep the Project Category as the default (File Storage).
• Provide a brief description of the project. This is used for summaries and reports.
• Set the Requested disk space (in GB) and the Requested number of files. The number of files should be between 100,000 and 200,000 per terabyte. If you request too many files, your request may be rejected.
• The expiration date is fixed to one year from approval and cannot be changed. Projects must be renewed annually.
• You may directly add CÉCI users to your project if you know their login. Alternatively, users can register themselves afterwards using the account management interface (“join an existing project”), in which case you will be notified of their registration.

Once the form is complete, click Send. Your request will be reviewed by the CÉCI team, and you will receive an email once the project is ready.

Additional Comments

The CÉCI Common Storage is not a scratch filesystem or a local home

Because the Common Storage is distributed (Ceph-based), performance is lower than the $LOCALSCRATCH and $GLOBALSCRATCH filesystems on individual clusters. Avoid writing or reading many small files, as IOPS performance will be lower than in your local $HOME directory.

The CÉCI Common Storage is not a long-term archive

Although data is replicated to protect against disk failure, there is no backup, similar to all CÉCI cluster filesystems. Only actively used data should be stored here. Long-term archival should be done using your university’s mass-storage facilities.

Use large files, or if not possible, use archives

Local filesystems are always faster than the Common Storage. Consider staging data in and out for your jobs:
- At the beginning of a job, decompress an archive from the Common Storage to local storage (Stage in).
- At the end of a job, compress results and store the archive in the Common Storage (Stage out).

Example of a 6.3 GB archive containing 50,000 files:
- Decompression from Common Storage to NIC5 $LOCALSCRATCH: 47 s vs. 14 m 26 s if copied without archiving
- Compression from NIC5 $LOCALSCRATCH to Common Storage: 31 s vs. 1 m 37 s without archiving