In order to keep filesystems from filling up and disrupting work, we use filesystem quotas to limit usage in certain areas by user or group. This also helps us observe growth in disk usage over time so we can plan future expansion.
By default, the filesystem quotas are as follows:
filesystem | quota (maximum total data size allowed) | file limit (maximum number of files allowed) |
---|---|---|
| 100 GiB per user | none |
| varies by lab/group | none |
| varies by lab/group | none |
| 10 TiB per user | 1,000,000 files or directories |
| 15 TiB per user* | none |
* scratch_gpu
is only available for labs whose PI has a primary or secondary appointment in a pre-clinical HMS department.
Checking Usage
You can use the quota
and du
commands to check filesystem usage.
Usage by User and Group
The quota
command on O2 will show your usage and usage by groups of which you are a member for directories (accessible on O2) that have quotas imposed.
Type quota
at the command prompt on any O2 system. The output will look something like:
/home [i] usage warning limit ===== ----- ------- ----- user mfk8 (uid 5005) 75GiB 95GiB 100GiB * /n/groups [f] usage warning limit ========= ----- ------- ----- group smith (gid 3204) 142GiB user mfk8 (uid 5005) 17GiB /n/groups/smith [f] usage warning limit =================== ----- ------- ----- directory 142GiB 200GiB clusters ======== [ f - itisimdcp05 as of 2021-05-10 13:00:01 ] based on default quota -- * [ i - itisimdcp10 as of 2021-05-10 13:00:00 ] usage exceeds limit --- !
You will see a number representing your individual storage usage in your /home
directory on the "user" line above the 100GiB quota on the "directory" line. Also, if you are a member of a group directory, you'll have a line for your usage above the "directory" line showing all group members' usage.
If you have reached a quota limit, you will see an exclamation mark or !
at the end of the line for the directory that has exceeded the quota.
The quota data is updated on an hourly basis. You can tell how recent the data you're viewing is from the timestamp at the bottom of the quota
output. It is possible to hit a quota limit (e.g. in your home directory or your group directory) but not have the output from the quota
command reflect this problem for about an hour due to the information being periodically updated.
scratch3 quotas
For data on /n/scratch3
, you need to use the scratch3_quota.sh
command:
$ /n/cluster/bin/scratch3_quota.sh Directory: /n/scratch3/users/m/mfk8 Space used: 0TiB used of 10TiB Files/directories: 1256 of 1000000
Note that "limit" is the total amount of space you are allowed to use. ("quota" is actually describing a "soft quota" where you get a warning but can still write. The /n/scratch3
filesystem doesn't use these.)
Note: It is against RC policy to artificially refresh last access time of any file located under /n/scratch3.
For more information on scratch3, please refer to the dedicated scratch3 wiki page.
scratch_gpu quotas
Quota utilization for /n/scratch_gpu
is reported by the command quota if used from a node where the /n/scratch_gpu
filesystem is available (login, transfer or compute-g nodes)
Usage by Directory
Another way to check usage is to total the size of files in a directory using the du
command. For example, you might want to see how much space your sub-directory in your group's shared directory is consuming:
To check the size of a directory (e.g.
/n/groups/smith/mydirectory
):Run the command:
du --apparent-size -hs /n/groups/smith/mydirectory
The output returned is the total size.
Note that
du
can take quite some time for directories containing large numbers (tens of thousands or more) of files, because it must check the size of every file to compute the total. In general, it is better to usequota
to find usage information, when possible, or at least to rundu
on sub-directories instead of top-level directories.
The
--apparent-size
option is required to find files' actual sizes. Without this option, the reported size will include data protection overhead (redundant copies of data on the O2 file server, which protects against hard drive failures).Please do not run
du
from a login node. Long running and computationally intensive processes will be killed on login nodes. To ensure that your command for checking directory usage is not interrupted, please rundu
from a compute node instead. You can use thesrun --pty
command to start an interactive job, and then rundu
once you have been allocated resources. More information on running SLURM jobs can be found on the Using Slurm Basic wiki page.
When you are over quota
How to tell you are over quota
If a shared group directory is over its quota, when you try to write a file to somewhere in that directory or a directory below it, you will get an error message. However, you will still be able to write to your home directory, or other group directories you may belong to.
Having a full home directory can lead to extra issues. In addition to not being able to write regular files, the computer may be unable to write invisible "housekeeping" files, which can lead to other problems. For example, on logging in, you may see an error like this:
/usr/bin/xauth: error in locking authority file /home/mfk8/.Xauthority
Also, when trying to edit files, you may get errors about an inability to write temporary files.
You can verify that you are over quota by running the quota
command. If you see an !
at the end of a line of output, then it means you have hit or exceeded a limit.
What to do when you are over quota
Use the commands above to confirm that you are above your quota, and delete data as needed to let you write new files again.
Note that the quota
command results are only updated hourly. If you were writing files very rapidly, the quota
command might not show a completely full quota. Also, deleting files won't immediately change the results from that command. If you delete 5 GiB of files, you should be able to write 5 GiB of new files in that location immediately, even if quota
hasn't caught up yet.
You can delete a whole directory with a command like rm -rf dir
. Please be careful when using a command like this: you could delete all of your files!
If you delete files in a snapshotted system by accident, see the Restoring Backups section on the Filesystems page to get them back within sixty days. On a scratch or temporary filesystem, there is no way to get files back.
Requesting a Quota Increase
Home folders will not be expanded. However, we are happy to make reasonable quota increases for your group or website folders. Please navigate to our Storage website to find the storage request forms. Links to storage request forms are located in the expandable blocks for each type of storage. When you fill out the storage request forms, please let us know the amount of additional space you would like and a reason for your increased storage needs. If you have any questions, please reach out to us.
Other Resources
For additional information on HMS RC storage offerings, and where O2 cluster users can store data, please reference the following pages: