Large Memory Computing
Debugging

Oscar's Filesystem

CCV uses IBM's General Parallel File System (GPFS). Users have a home, data, and scratch space.

home ~

  • 20GB of space

  • Optimized for many small files

  • Nightly backups (30 days)

  • Quota is per individual user

  • Grace period of 14 days

data ~/data

  • Each PI gets 256GB for free

  • Optimized for reading large files

  • Nightly backups (30 days)

  • Quota is by group

  • Grace period of 14 days

scratch ~/scratch

  • 512GB of space - contact [email protected] increase on a temporary basis

  • Optimized for reading/writing large files

  • NO BACKUPS

  • Purging: files not accessed for 30 days may be deleted

  • Quota is per individual user

  • Grace period of 21 days

Files not accessed for 30 days will be deleted from your scratch directory. This is because scratch is high performance space. The fuller scratch is the worse the read/write performance. Use ~/data for files you need to keep long term.

The scratch purge is on individual files. It is by 'atime' which is when the file was last read. You can use 'find' to find files that are at risk of being purged, e.g. to find files in the current directory that have not been accessed in the last 25 days:

find . -atime +25

A good practice is to configure your application to read any initial input data from ~/data and write all output into ~/scratch. Then, when the application has finished, move or copy data you would like to save from ~/scratch to ~/data.

Note: class or temporary accounts may not have a ~/data directory!

To see how much space you have on Oscar you can use the command myquota. Below is an example output

Block Limits | File Limits
Type Filesystem Used Quota HLIMIT Grace | Files Quota HLIMIT Grace
-------------------------------------------------------------|--------------------------------------
USR home 8.401G 20G 30G - | 61832 524288 1048576 -
USR scratch 332G 512G 12T - | 14523 323539 4194304 -
FILESET data+apollo 11.05T 20T 24T - | 459764 4194304 8388608 -

You can go over your quota up to the hard limit for a grace period. This grace period is to give you time to manage your files. When the grace period expires you will be unable to write any files until you are back under quota.

There is a quota for space used and for number of files. If you hit the hard limit on either of these you will be unable to write any more files until you are back under quota.