File Storage and I/O
Disk Quota Change Request Form
Hopper File Systems
The Hopper system has 5 different file systems mounted which provide different levels of disk storage, I/O performance and file permanence. The table below describes the various Hopper file systems:
| File System | Home | Local Scratch | Global Scratch | Project |
|---|---|---|---|---|
| Environment Variable Definition |
$HOME | $SCRATCH $SCRATCH2 |
$GSCRATCH | No environment variable /project/projectdirs/ |
| Description |
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| Default Quota |
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| Intended Purpose |
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| Peak Performance | Low, ~100 MB/sec | 35 GB/sec for each | 15 GB/sec | 15 GB/sec |
| Purged? | No | Yes, files older than 12 weeks are purged | Yes, files older than 12 weeks are purged | No |
Scratch Directories
Hopper is configured with two distinct scratch file systems named /scratch and /scratch2. Each user therefore has access to two scratch directories, which should always be referenced using the environment variables $SCRATCH and $SCRATCH2. Both file systems are available from all nodes, and are tuned for high performance. Users may run out of either scratch file system, but are encouraged to choose one or the other for their primary work.
There is a single (large) quota (space and inode) for each user that applies to the combined contents of $SCRATCH and $SCRATCH2. If your combined usage of $SCRATCH and $SCRATCH2 exceeds your quota, you will not be able to submit batch jobs until you reduce your combined usage.
The "myquota" command (with no options) will display a user's current usage and quota. NERSC sometimes grants temporary quota increases for legitimate purposes. To apply for such an increase, please see Disk Quota Increase Form.
Purging of "old" files from $SCRATCH and $SCRATCH2 began on Wednesday, March 14. Files in your $SCRATCH and $SCRATCH2 that are older than 12 weeks (defined by last access time) are removed. Please make sure to back up your important files (e.g. to HPSS).
Do Not Use /tmp explicitly
WARNING: Do not attempt to explicitly use a file system named /tmp. Your job may fail or be deleted if it writes to /tmp. Some software tools (editors, compilers, etc.) use the location specified by the $TMPDIR environment variable to store temporary files. Additionally, Fortran codes which open files with status="scratch" will write those files into $TMPDIR. On many Unix systems, $TMPDIR is set to /tmp. NERSC has set $TMPDIR to be $SCRATCH. Please do not redefine $TMPDIR!
