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This area is conceived for hosting working data files whenever the I/O operations constitute the bottleneck for your applications. It behaves well both when I/O is performed accessing large blocks of data, and for frequent and small I/O operations. Due to the limited size of the area, the main space for maintaining the data resulting from batch processing is the corresponding $WORK area.
There is one $FAST area for each active project on the machine. The fixed quota is 1 TB per project, and due to the total dimension of the storage, extensions cannot be considered. The owner of the main directory is the PI (Principal Investigator) of the project. All collaborators are allowed to read/write in there. Collaborators are advised to create a personal directory in $WORK $FAST for storing their personal files. By default, the personal directory will be protected (only the owner can read/write), but protection can be easily modified, for example by allowing write permission to project collaborators through chmod through chmod command. This second approach does not affect global files security.
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Each compute node is equipped with a local storagearea whose dimension differs depending on the cluster (please look at the specific page of the cluster for more details).
When a job starts, a temporary area is defined on the storage local to each compute node. On MARCONI and GALILEO100:
TMPDIR=/scratch_local/slurm_job.$SLURM_JOB_ID
which can be used exclusively by Differently from the other CINECA clusters, on LEONARDO the job's owner. During your jobs, you can access the area with the (local) variable $TMPDIR. In your sbatch script, for example, you can move the input data of your simulations to the $TMPDIR before the beginning of your run and also write on $TMPDIR your results. This would further improve the I/O speed of your code.However, the directory is removed at the job's end;temporary area is managed by the slurm job_container/tmpfs plugin, which provides an equivalent job-specific, private temporary file system space, with private instances of /tmp and /dev/shm in the job's user space:
TMPDIR=/tmp
visible via the command "df -h /tmp". If more jobs share one node, each one will have a private /tmp in the job's user space. The tmpfs are removed at the end of the job (and all data will be lost).
Whatever the mechanism, the TMPDIR can be used exclusively by the job's owner. During your jobs, you can access the area with the (local) variable $TMPDIR. In your sbatch script, for example, you can move the input data of your simulations to the $TMPDIR before the beginning of your run and also write on $TMPDIR your results. This would further improve the I/O speed of your code.
However, the directory is removed at the job's end; hence always remember to save the data stored in such area to a permanent directory in your sbatch script at the end of the run. Please note that the area is located on local disks, so it can be accessed only by the processes running on the specific node. For multinode jobs, if you need all the processes to access some data, please use the shared filesystems $HOME, $WORK, $CINECA_SCRATCH.
Differently from the other CINECA clusters, thanks to the job_container/tmpfs plugin the local storage is considered a "resource" on LEONARDO, and can be explicitly asked on the diskful nodes only (DCGP and serial nodes) via the sbatch directive or srun option "-gres=tmpfs:XX" (see the specific Disks and Filesystems section on LEONARDO's User Guide for the allowed maximum values). For the same reason, the requested amount of gres/tmpfs resource contributes to the consumed budget, changing the number of accounted equivalent core hours, see the dedicated section on the Accounting on CINECA clusters hence always remember to save the data stored in such area to a permanent directory in your sbatch script at the end of the run. Please note that the area is located on local disks, so it can be accessed only by the processes running on the specific node. For multinode jobs, if you need all the processes to access some data, please use the shared filesystems $HOME, $WORK, $CINECA_SCRATCH.
$DRES: permanent, shared (among platforms and projects)
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