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Home directory volume (/home)

HOME storage space

For each account with access to the Aristotle University of Thessaloniki's computing cluster "Aristotle" a home directory is created in the storage volume hpc_workdir which can only be accessed by that account from the path /home/<first_letter>/<username>.

The available space for each new account is equal to 20GB and is set as a disk quota in the total storage resources. The specified limit may be modified to expand the available space, if necessary, after contacting hpc-support@auth.gr. After one year from the request, if the tasks for which additional storage space is required are completed, the storage is reverted to its original size.

After connecting to your account via ssh, you can see the path where your account's home directory is located using the following command:

# echo $HOME

You can check the available storage and the limits set for your account using the following command:

# quota -s -f /home

To see detailed information about the storage reserved by each individual directory in $HOME of your account, you can use the NCurses Disk Usage analyzer as follows:

# module load gcc/9.2.0 ncdu
# ncdu

Snapshot Policy

For data availability purposes, two daily and two weekly snapshots of each user's /home directory are taken based on the "Aristotle" computational cluster's snapshot policy. These snapshots are stored in the .snapshot/ hidden folder located in /home and every subdirectory.

Access to snapshots

To access the snapshot folders we follow the same procedure as for any other folder

# cd .snapshot/
# cd <snapshot>.<date>/

File Restoration

In case of a file being deleted by mistake, we enter the folder of the latest snapshot and execute the following command :

# cp -p <filename> ../../

With which we copy the file we deleted to the folder where we had it. Note that if we want to restore a folder, we use the same command with the following modification :

# cp -rp <foldername> ../../

Scratch volume (/scratch)

SCRATCH storage space

For each account with access to the Aristotle University of Thessaloniki's computing cluster "Aristotle" a scratch directory is created in the storage volume scratch_c which can only be accessed by that account from the path /scratch/<first_letter>/<username>.

The storage volume scratch_c consists of a set of SSD disks and is used to perform tasks, but not for long-term data storage. Data that remains in the scratch volume for more than 30 days will be deleted by an automatic mechanism to ensure the best possible performance of the storage. Therefore, data resulting from job execution should be moved to the home directory or to an external storage.

To move to the scratch directory of your account you can use the following command:

# cd $SCRATCH

cn50_nvme volume (/mnt/cn50_nvme/tmp)

The storage volume cn50_nvme is an NVMe storage system accessible from the ampere partition and the login nodes. It supports tasks running on the ampere partition that require high-speed file access (I/O).

To move to cn50_nvme, you can use the following command:

# cd /mnt/cn50_nvme/tmp/

Please note that this volume does not have an automatic data deletion mechanism like the scratch space, so files stored here remain without any time limitation. However, we kindly ask that you do not use this space for storing important data, as once full, the management team reserves the right to delete files without prior notice. This space is intended solely for temporary files, as indicated by the name "tmp".

Additionally, this space is accessible to all users. If you wish to protect the files within a folder from other users, you can use the following command to modify the folder's access permissions:

# chmod 770 <directory_name>

Other storage volumes

Also, the possibility of shared access to storage volumes for research teams is supported.