Large datasets are often stored off-cluster on departmental servers, Storage@Yale, in cloud storage, etc. Since the permanent home of the data remains on off-cluster storage, you need to transfer a working copy to the cluster temporarily. When your computation finishes, you would then remove the copy and transmit the results to a more permanent location.
A sample workflow using
rsync would be:
# copy data to temporary cluster storage [netID@cluster ~]$ rsync -avP netID@department_server:/path/to/data $HOME/scratch60/ # process data on cluster [netID@cluster ~]$ sbatch data_processing.sh # return results to permanent storage for safe-keeping [netID@cluster ~]$ rsync -avP $HOME/scratch60/output_data netID@department_server:/path/to/outputs/
The working copy of the data can then be removed manually or left to be deleted (which will happen automatically after 60-days). See the Archive Data and Transfer Data pages for more ways to move data efficiently to and from the clusters.
Both Grace and Farnam have dedicated data transfer partitions (named
transfer) designed for staging data onto the cluster.
All users are able to submit jobs to these partitions. Note each users is limited to running two transfer jobs at one time.
If your workflow requires more simultaneuous transfers, contact us for assistance.
We recommend using
tmux to launch interactive transfers so that you are able to log out and leave the job running in the background.
# enter tmux shell [netID@grace1 ~]$ tmux # launch transfer job [netID@grace1 ~]$ srun --pty --partition transfer --cpus-per-task=1 --time=6:00:00 bash # start transfer [netID@c01n03 ~]$ rsync -avP netID@department_server:/path/to/data $HOME/scratch60/
tmuxsession. This will leave your transfer running in the background inside the
tmuxsession. For more details about how to use
tmux, look at our guide here.
Transfers as Batch Jobs
sbatch script for an
rsync transfer is show here:
#!/bin/bash #SBATCH --partition=transfer #SBATCH --time=6:00:00 #SBATCH --cpus-per-task=1 #SBATCH --job-name=my_transfer #SBATCH --output=transfer.txt rsync -av netID@department_server:/path/to/data $HOME/scratch60/
remote.host.yale.eduto your scratch60 directory. Note, this will only work if you have set up password-less logins on the remote host.
Transfer Job Dependencies
sbatch options that allow you to hold a job from running until a previous job finishes.
These are called Job Dependencies, and they allow you to include a data-staging step as part of your data processing pipe-line.
Consider a workflow where we would like to process data located on a remote server. We can break this into two separate Slurm jobs: a transfer job followed by a processing job.
#!/bin/bash #SBATCH --partition=transfer #SBATCH --time=6:00:00 #SBATCH --cpus-per-task=1 #SBATCH --job-name=my_transfer rsync -av netID@department_server:/path/to/data $HOME/scratch60/
#!/bin/bash #SBATCH --partition=day #SBATCH --time=6:00:00 #SBATCH --cpus-per-task=1 #SBATCH --job-name=my_process module purge module load miniconda conda activate my_env python $HOME/process_script.py $HOME/scratch60/data
First we would submit the transfer job to Slurm:
$ sbatch transfer.sbatch Submitted batch job 12345678
Then we can pass this jobID as a dependency for the processing job:
$ sbatch --dependency=afterok:12345678 process.sbatch Submitted batch job 12345679
$ squeue JOBID PARTITION NAME USER ST TIME NODES NODELIST(REASON) 12345679 day process netID PD 0:00 1 (Dependency) 12345678 transfer transfer netID R 0:15 1 c01n04
Storage@Yale shares are mounted on the transfer partition, enabling you to stage data from these remove servers.
The process is somewhat simpler than the above example because we do not need to
rsync the data, and can instead use
Here, we have modified the
transfer.sbatch file from above:
#!/bin/bash #SBATCH --partition=transfer #SBATCH --time=6:00:00 #SBATCH --cpus-per-task=1 #SBATCH --job-name=my_transfer cp /SAY/standard/my_say_share/data $HOME/scratch60/
This will transfer
data from the Storage@Yale share to
scratch60 where it can be processed on any of the compute nodes.