Scratch Space

Scratch space is the primary location for data. The name of the scratch space takes the form /scr[first two letters of the machine name][scratch device number]. The name for the second scratch device on spur is thus: /scrsp2.

These drives are large, ranging in size from 1.7 GB - 40 GB and are attached to all of the main computers at SEP. In order to minimize network traffic, try to write your data to scratch drives attached to the machine you are running on. This will make your job run faster, minimize the chance of the job failing because of network problems, and keep the whole network running at a higher level. This is generally taken care of for you by your /.datapath file.

A couple of cautionary notes about scratch devices:

• Auto-erase: Files which have not been accessed for a while are automatically erased. The erasure period varies from 2 weeks to a month depending on the drive. So if something is critical to you it is much better to leave it on your personal device.
• Hogging: If a scratch device gets too full, the top four users of the device will be sent a message. It is fine to to be the major user of scratch space occasionally, but avoid hogging for long periods.