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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

default quota

file limit

/home

100 GB per user

none

/n/groups

varies

none

/n/data#

varies

none

/n/scratch2

10 TB

1,000,000 files or directories


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:

  /n/groups [f]                                    usage    warning    limit   
  =======                                          -----    -------    -----   
  group smith                        (gid 3449)      14G                       
   user mfk8                         (uid 5005)      73M                       
    directory                                       2.9P       3.0P     3.0P   

  /n/groups/smith [f]                              usage    warning    limit   
  ================                                 -----    -------    -----   
    directory                                        14G        90G     100G   

  /home [d]                                        usage    warning    limit   
  =====                                            -----    -------    -----   
   user mfk8                         (uid 5005)      65K                100G * 
    directory                                        73T        78T      80T   

  clusters
  ========
  [ d - itisimdcp03 as of 2017-09-11 14:00:00 ]    based on default quota -- * 
  [ f - itisimdcp05 as of 2017-09-11 14:00:00 ]       usage exceeds limit --- !

Usually you'll see a number above the quota for the "user" line in your /home directory, or for the "group" line in a group directory.

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.

scratch2 quotas

On /n/scratch2, you need to use the lfs quota command:

mfk8@login02:~>lfs quota -h /n/scratch2
Disk quotas for user mfk8 (gid 1234567):
     Filesystem    used   quota   limit   grace   files   quota   limit   grace
    /n/scratch2      0k      0k     10T       -       0       0 1000000       -
Disk quotas for group mfk8 (gid 2345678):
     Filesystem    used   quota   limit   grace   files   quota   limit   grace
    /n/scratch2      0k      0k      0k       -       0       0       0       -

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/scratch2 filesystem doesn't use these.)

Note: It is against RC policy to artificially refresh last access time of any file located under /n/scratch2.

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 use quota to find usage information, when possible, or at least to run du 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).

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.

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. So 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. Still, if you delete 5 GB of files, you should be able to write 5 GB 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 submit a request via our web site and let us know the amount of additional space you would like and a reason for your increased storage needs.

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