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Permutter Scratch is an all-flash Lustre file system designed for high performance temporary storage of large files. It is intended to support intensive I/O for jobs that are being actively computed on the Perlmutter system. We recommend that you run your jobs, especially data intensive ones, from the Perlmutter Scratch File System.
The Perlmutter Scratch File system should always be referenced using the environment variable
$PSCRATCH. It is available from all Permutter compute nodes and is tuned for high performance.
If your scratch usage exceeds your quota, you will not be able to write to the file system until you reduce your usage.
The Perlmutter Scratch File System is an all-flash file system. It has 35 PB of disk space, an aggregate bandwidth of >5 TB/sec, and 4 million IOPS (4 KiB random). It has 16 MDS (metadata servers), 274 I/O servers called OSSs, and 3,792 dual-ported NVMe SSDs.
For large files you should stripe your files across multiple OSTs. Please see our Lustre striping page for details.
All NERSC users should backup important files on a regular basis. Ultimately, it is the user's responsibility to prevent data loss.
The scratch file system is subject to purging. Please make sure to back up your important files (e.g. to HPSS).
Perlmutter scratch directories are purged. Perlmutter scratch directories may be deleted after a user is no longer active.