Scratch Policy

$SCRATCH VARIABLE

A global variable called $SCRATCH exists on the FASRC Cannon and FASSE clusters which allows scripts and jobs to point to a specific directory in scratch regardless of any changes to the name or path of the top-level scratch filesystem. This variable currently points to /n/netscratch so, for example, one could use the path $SCRATCH/jharvard_lab/Lab/jsmith in a job script. This will have the added benefit of allowing us to change scratch systems at any time without your having to modify your jobs/scripts.

SCRATCH FILESYSTEM

RC maintains a large, shared temporary scratch filesystem for general use for high input/output jobs at /n/netscratch .  Each lab is allotted 50TB of scratch space for its use in their jobs. This is temporary high-performance space and files older than 90 days will be deleted through a periodic purge process. This purge can run at any time, especially if scratch is getting full and is also often run at the start of the month during our monthly maintenance period.

There is no charge to labs for scratch, but please note that it intended as volatile, temporary scratch space for transient data and is not backed up. If your lab has concerns or needs regarding scratch space or usage, please contact FASRC to discuss.

Modifying file times (via touch or other process) when initially placing data in scratch is allowed, however doing so subsequently to avoid deletion is an abuse of the filesystem and will result in administrative action from FASRC. To reiterate, you may initially modify the file date(s) on new data so that it is not in the past, but should not modify it further.  If you have longer-term needs, please contact us to discuss options.