Quotas provide a way to restrict or track the disk space and number of files used by a user, group, or qtree. Quotas are specified using the /etc/quotas file, and are applied to a specific volume or qtree.
Why you use quotas
You can use quotas to limit resource usage, to provide notification when resource usage reaches specific levels, or simply to track resource usage.
Overview of the quota process
Quotas can cause Data ONTAP to send a notification (soft quota) or to prevent a write operation from succeeding (hard quota) when quotas are exceeded.
Quota targets and types
Quota targets determine whether a quota operates on a user, group, or qtree; targets determine the quota type.
Special kinds of quotas
You use default, explicit, derived and tracking quotas to manage disk usage in the most efficient manner.
How quotas work with users and groups
When you specify a user or group as the target of a quota, the limits imposed by that quota are applied to that user or group. However, some special groups and users are handled differently. In addition, some rules apply to user and group quotas.
How quotas work with qtrees
You can create quotas with a qtree as their target; these quotas are called tree quotas. You can also create user and group quotas for a specific qtree. In addition, quotas for a volume are sometimes inherited by the qtrees contained by that volume.
Differences among hard, soft, and threshold quotas
Hard quotas (Disk and Files fields) impose a hard limit on system resources; any operation that would result in exceeding the limit fails. The soft quotas (Threshold, Soft Disk and Soft Files fields) enable you to receive a warning when users reach a certain resource level without affecting their data access, so you can take appropriate action before the quota is exceeded.
How the quotas file works
The quotas file, found in the /etc directory, contains one or more entries specifying limit or tracking quotas for qtrees, groups, and users. The file can contain default (general) and specific entries.
About activating or reinitializing quotas
Reinitialization causes the quotas file to be scanned and all quotas for that volume to be recalculated. You use the quota on command to activate or reinitialize quotas. Knowing how quota initialization works can help you manage your quotas less disruptively.
About modifying quotas
After you make changes to your quotas file, you need to request Data ONTAP to read the quotas file again and incorporate the changes. There are two ways to do this, depending on the contents of your quotas file.
How qtree changes affect quotas
When you delete, rename, or change the security style of a qtree, the quotas applied by Data ONTAP might change, depending on the current quotas being applied.
How quota reports work
Quota reports enable you to see what quotas Data ONTAP is applying. You can change the format of the quota report and how user IDs are displayed using the options for the quota report command.
Progressive quota examples
Following through a series of progressive examples can help you to understand how to create your quotas file and read your quota reports.
