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home > support > FAQ > group_quotas

Project Groups and Disk Quotas


Q: Why are files which I create being charged to the wrong disk quota?

Disk quotas for consortia and project groups on HPCx are implemented using UNIX group quotas. Each consortium initially has one UNIX group (GID), and every member of the consortium belongs to this; we call this the main project group.

When another project group within a consortium is created with a disk quota of its own, a new UNIX group is assigned to it. At the same time, a directory for it is created on each volume where it has a quota of its own: /home or /work. For example, if the consortium code is x01, and a project group x01-abc is created with a quota on /work, then a directory /hpcx/work/x01/x01-abc will be created.

Every user who is a member of a project group will have a directory within the directory for that project group. So if user 'max' is a member of the /x01-abc group, they will have a directory /hpcx/work/x01/x01-abc/max

Any file created in this directory will normally be in the x01-abc group, and so will count against x01-abc's quota. If you create another directory within x01-abc, it will also belong to that group, and so will all files created there, and so on.

So if you follow this scheme, all the files you create will count against the right quota. There are one or two things which can cause problems.

The first is that people belong to more than one project group. In particular, each user belongs to the main project group of the consortium (in this case, x01) as well as any other project groups. This means that our user 'max', for example, will have a directory /x01/x01/max, as well as /x01/x01-abc/max. If 'max' goes to /x01/x01/max and creates a file there, it will normally belong to the main project group, and so will count against the quota for x01, not x01-abc.

When you log in, you will initially be in your main project group directory. If you want to create files which belong to another project group, you must first go to that directory.

(In fact, some people use the same account to work in more than one consortium. When you log in, you will be in one of these; to create files which belong to another, you must go to the appropriate directory.)

Another problem is using the cp -p (or scp -p) commands. If you do this, the file you create will have the same group as the original it's copied from, even if it's in a directory which belongs to another group.

You can always check what group a file belongs to by using the 'ls -l' command. If you find files that aren't in the 'correct' group, you can change them by using the 'chgrp' command. For example:

chgrp -R x01-abc mine

...will change the group of 'mine' and all the directories and other files inside it to group 'x01-abc'.

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