Disk Quotas

Principles

Quotas guarantee fair access to disk resources. They prevent the situation where a group of users could consume all of the disk space, thereby preventing other users from working. At IDRIS, quotas limit both the quantity of disk space and the number of files (in inodes) of each project 1) . There is not a limit for each individual user.

When group quotas are reached, no more files can be created: Doing this could disturb the jobs being run by your group. Attention: Modification of a file after quotas have been reached may result in the file being erased.

How to know your current disk space consumption and quotas

The command quota_u allows you to obtain the current consumption and quotas for the $HOME. The option -w allows you to obtain the same information for $WORKDIR. The $TMPDIR space is not subjected to quotas.

  • The soft quota represents your disk space allocation. When this limit has been reached, you have a period of one week to decrease the disk occupation to within the limit. If disk occupation is not reduced during this period, no group member can create any more files.
  • The hard quota is the disk space limit which the system imposes. If this limit is reached, it is no longer possible to create any files.
  • The quota_u command displays the consumption per user. This consumption includes all the files belonging to a user, even if they are not located in his/her personal spaces. It takes into account files created in spaces shared by the group ($COMMONDIR) or located in personal spaces of other users.
  • Information from the quota_u command is not updated in real time.

When quotas are exceeded

When a group has exceeded the quota on Ergon, an e-mail is sent to each member of the group. On the other machines, however, no warning e-mail is sent; nevertheless, you are informed by error messages when you manipulate files in the concerned disk space (“disk quota exceeded”).

In case of blockage, it is necessary to delete files or move them to another space such as the $WORKDIR or to the Ergon archiving machine if appropriate. The project manager (or designated replacement) can request a quota increase on the IDRIS extranet site.

1) It is necessary to limit the number of files in order to guarantee an optimal usage of the file systems.