File System Quotas and Purging¶

NERSC sets quotas on file systems shown in the table below. Purged file system are purged of files that have not been accessed in the time period shown below.

Overview¶

Policy¶

NERSC data management policy.

Quotas¶

You may briefly exceed your quota on Perlmutter scratch by as much as 10 TB for up to 24 hours before no new data can be written. This is known as a 'grace period'. When you are above your 20 TB quota, showquota --grace will show how much time you have left in your grace period before the file system becomes read-only.

Quota tools¶

NERSC offers two separate tools to retrieve your quota status:

• showquota, which works on Perlmutter and the Data Transfer Nodes, offers more control over the file systems to retrieve quota for, works with all file systems general users have access to (including the HPSS archive!) and provides many features, such as overquota grace times and JSON output.

• myquota, cfsquota, prjquota, and cmnquota are relic commands from an older system. They are now symlinks to showquota, so we encourage users to switch to using showquota instead.

To see current usage for the Home and Scratch file systems you can just type:

showquota

You can also exclude the Home and Scratch file systems from the default file systems to report quotas for with -N/--no-default-fs.

For the Community File System you can specify the projects you want to check quota for with:

showquota PROJECT [PROJECT [..]]

For the Common File System you can add --cmn, and showquota will report quotas for all projects you pass as arguments:

showquota --cmn PROJECT [PROJECT [..]]

The --hpss/--hpssquota option makes showquota report HPSS Archive quotas for all projects the user is part of:

$ showquota --hpss
+----------------------------------------------+------------+-------------+----------------+------------+-------------+----------------+
|                                  File system | Space used | Space quota | Space used (%) | Inode used | Inode quota | Inode used (%) |
+----------------------------------------------+------------+-------------+----------------+------------+-------------+----------------+
| username usage on HPSS charged to project123 |   23.74TiB |     1.44PiB |           1.6% |          - |           - |              - |
| username usage on HPSS charged to project456 |      0.00B |   133.00TiB |           0.0% |          - |           - |              - |
+----------------------------------------------+------------+-------------+----------------+------------+-------------+----------------+

Or alternatively you can specify full paths, and mix and match different quota queries into a single one (unfortunately there's no way to request HPSS quotas by path, only by enabling the --hpss keyword):

$ showquota --no-default-fs --full-path $CFS/dasrepo /global/common/software/dasrepo
+---------------------------------+------------+-------------+----------------+------------+-------------+----------------+
|                     File system | Space used | Space quota | Space used (%) | Inode used | Inode quota | Inode used (%) |
+---------------------------------+------------+-------------+----------------+------------+-------------+----------------+
|       /global/cfs/cdirs/dasrepo |   98.54TiB |   110.00TiB |          89.6% |     32.51M |     100.00M |          32.5% |
| /global/common/software/dasrepo |   72.99GiB |   100.00GiB |          73.0% |    819.56K |       2.00M |          41.0% |
+---------------------------------+------------+-------------+----------------+------------+-------------+----------------+

Different output formats and unit of measurements are available, see showquota --help.

For scripting purposes we suggest to use the JSON formatting option -J/--json, which can be quite powerful when paired with e.g. the jq utility:

$ showquota -J dasrepo nstaff |jq '.[] | "\(.fs) \(.space_perc)"'
"home 0.2%"
"pscratch 0.7%"
"dasrepo 0.9%"
"nstaff 0.4%"

The -L/--limit/--grace option shows how much more storage and inodes you can temporarily write above your quota and how much time you have left before no new data can be written.

showquota is a Python script, and has been designed with composability in mind, so you can use it in your own Python scripts by making it available in your $PYTHONPATH variable, e.g.:

$ PYTHONPATH="$(dirname $(which showquota)):$PYTHONPATH" python3
>>> import showquota
>>> stats = showquota.report('project123', full_path=True)
>>> stats
[/global/cfs/cdirs/project123: 70.1% storage - 87.9% inode]
>>> stats[0].is_overquota()
False

Feel free to reach out by opening a ticket for more details.

Increases¶

If you or your project needs additional space for your scratch file system or HPSS you may request it via the Disk Quota Increase Form.

Quotas on the Community File System are determined by DOE Program Managers based on information PIs supply in their yearly ERCAP requests. If you need a mid-year quota increase on the Community File System, please use the Disk Quota Increase Form link above and we will pass the information along to the appropriate DOE Program Manager for approval.

Purging¶

Some NERSC file systems are purged. This means the files not read (i.e. atime is updated) within a certain time period are automatically deleted. You can see the time period for the purged file systems at NERSC in the overview table. When a purge is done, a file named .purged.<date> is left behind. This is a text file that holds the names of the files that have been removed. These .purged files will not be deleted by our purges to make sure a record of purging activities is retained. Touching files or other actions intended to circumvent the purge are forbidden by NERSC policy.

If you want to see the purged files from $SCRATCH you can do the following, it will report a timestamp of when the purge was performed. Note files from $SCRATCH can't be retrieved since there is no backup, however you can see what files were purged if you cat the content of file.

adele@perlmutter> ls $SCRATCH/.purged*
/pscratch/sd/a/adele/.purged.20210125  /pscratch1/sd/a/adele/.purged.20210822

Deleting your own files¶

To remain under quota, it could be useful to remove files from a directory. It can be non-trivial to find large files, especially if they are in a hidden directory.

Finding and deleting files on CFS¶

The Data Dashboard can be used to find large files in the Community File System. The dashboard shows disk space and inode usage for global directories at NERSC to which you have access as PI, PI proxy, or user. Click on the "My Files and Dirs" button for a list of your largest files in each directory.

Finding and deleting files in your home directory¶

The find command can help you discover which files are taking up the most space in your directory.

In the below example, user adele wants to find all files (-type f) in the current directory (.) and sub-directories that are at least 10 MB in size (-size +10M).

adele@perlmutter:~> find . -type f -size +10M
./.bazel/bin/bazel-real
./train/IntroToBB/examples/IOR
./test/run41/hello-coforall_real
./test/run41/hello1cori
./test/run41/hello2cori
./test/run41/hellocori
./test/run41/test

Note from this output that find can list files that are in hidden directories (such as the .bazel directory in the first line of output).

Adele is surprised that the IOR file is so large. An ls -lh confirms it:

adele@perlmutter:~> ls -lh ./train/IntroToBB/examples/IOR
-rwxrwx--- 1 adele adele 12M Jul 27  2017 ./train/IntroToBB/examples/IOR

To list the sizes of all the files above 10 MB in size, Adele can issue the command find . -type f -size +10M -exec ls -lh {}.

Adele realizes that all the files listed are not necessary and can be deleted. Furthermore, the entire .bazel directory can be deleted.

adele@perlmutter:~> showquota
+-------------+------------+-------------+----------------+------------+-------------+----------------+
| File system | Space used | Space quota | Space used (%) | Inode used | Inode quota | Inode used (%) |
+-------------+------------+-------------+----------------+------------+-------------+----------------+
|        home |   36.14GiB |    40.00GiB |          90.4% |     63.41K |       1.00M |           6.3% |
|    pscratch |   14.58GiB |    20.00TiB |           0.1% |     65.53K |      10.00M |           0.7% |
+-------------+------------+-------------+----------------+------------+-------------+----------------+
adele@perlmutter:~> rm -rf ./.bazel ./train/IntroToBB/examples/IOR 
./test/run41/hello-coforall_real ./test/run41/hello1cori ./test/run41/hello2cori
./test/run41/hellocori ./test/run41/test
adele@perlmutter:~> showquota
+-------------+------------+-------------+----------------+------------+-------------+----------------+
| File system | Space used | Space quota | Space used (%) | Inode used | Inode quota | Inode used (%) |
+-------------+------------+-------------+----------------+------------+-------------+----------------+
|        home |   16.62GiB |    40.00GiB |          41.6% |     62.93K |       1.00M |           6.3% |
|    pscratch |   14.58GiB |    20.00TiB |           0.1% |     65.53K |      10.00M |           0.7% |
+-------------+------------+-------------+----------------+------------+-------------+----------------+