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Scratch filesystems are a shared resource available for the convenience of all users. Therefore, files on these filesystems are subject to deletion after a certain lifespan as determined by the HPC policy committee. Home account storage and purchased storage are not subject to this policy.

/localscratch

login nodes

On /localscratch, the allowed file lifespan is 30 days after the file was last accessed, where each file's age is the time elapsed since its access timestamp ("atime"). An automated cleanup process runs periodically on each node to delete files whose atime has reached the maximum lifespan.

compute nodes

Cleaning of /localscratch on compute nodes is done on an opportunistic basis, cleaning when no jobs are on the node. However, if the space becomes limited, the node will go into an alarm state and will then be cleaned.

If your job writes data to /localscratch, please retrieve everything you need and remove unneeded files as the last part of the job, because it's difficult to access that same compute node after a job exits! A compute node can become unavailable if its /localscratch filesystem becomes too full. If that happens, all files will be removed from /localscratch without considering lifespan in order to restore the compute node to service. For more information on using localscratch see Advanced Job Submission#localscratch.

/nfsscratch

On /nfsscratch, the allowed file lifespan is 60 days after first being written, where each file's age is the time elapsed since its creation timestamp ("crtime") which is tracked on the fileserver. An automated cleanup process will run periodically on the server to delete files whose crtime has reached the maximum lifespan. This space is provided by a single ZFS storage server connected via NFS. It is best suited to large streaming I/O, reading or writing large data sequentially to or from a small number of files.

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