Quotas provide a way to restrict or track the disk space and number of files used by a user, group, or qtree. Quotas are applied to a specific FlexVol volume or qtree.
Why you use quotas
You can use quotas to limit resource usage in FlexVol volumes, to provide notification when resource usage reaches specific levels, or to track resource usage.
Overview of the quota process
Quotas can be soft or hard. Soft quotas cause Data ONTAP to send a notification when specified thresholds are exceeded, and hard quotas prevent a write operation from succeeding when specified thresholds are exceeded.
What quota rules, quota policies, and quotas are
Quotas are defined in quota rules specific to FlexVol volumes. These quota rules are collected together in a quota policy of a Storage Virtual Machine (SVM), and then activated on each volume on the SVM.
Quota targets and types
Quotas have a type: they can be either user, group, or tree. Quota targets specify the user, group, or qtree for which the quota limits are applied.
Special kinds of quotas
You use default, explicit, derived and tracking quotas to manage disk usage in the most efficient manner.
How quotas are applied
Understanding how quotas are applied enables you to configure quotas and set the expected limits.
Considerations for assigning quota policies
A quota policy is a grouping of the quota rules for all the FlexVol volumes of a Storage Virtual Machine (SVM). You must be aware of certain considerations when assigning the quota policies.
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. There are different ways to specify IDs for users, depending on your environment.
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 FlexVol volume are sometimes inherited by the qtrees contained by that volume.
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 quotas are activated
New quotas and changes to quotas do not take effect until they are activated. Knowing how quota activation works can help you manage your quotas less disruptively.
How you can view quota information
You can use quota reports to view details such as the configuration of quota rules and policies, enforced and configured quotas, and errors that occur during quota resizing and reinitialization.
Difference in space usage displayed by a quota report and a UNIX client The value of used disk space that is displayed in a quota report for a FlexVol volume or qtree can be different from the value displayed by a UNIX client for the same volume or qtree. The difference in usage values is because of the difference in methods followed by the quota report and the UNIX commands for calculating the data blocks in the volume or qtree.
Setting up quotas on an SVM with FlexVol volumes
To set up quotas on a new Storage Virtual Machine (SVM, formerly known as Vserver) with FlexVol volumes, you must create a quota policy, add quota policy rules to the policy, assign the policy to the SVM, and initialize quotas on each FlexVol volume on the SVM.
Modifying (or Resizing) quota limits
When you make changes to the size of existing quotas, you can resize the quotas on all affected volumes, which is faster than reinitializing quotas on those volumes.
Reinitializing quotas after making extensive changes
When you make extensive changes to existing quotas; for example, by adding or deleting quotas for targets that have no enforced quotas— you must make the changes and re-initialize quotas on all affected volumes.
Verifying status of quota upgrades
When you initiate the transition of a FlexVol volume containing quotas from Data ONTAP 7.3.x to a clustered Data ONTAP version such as Data ONTAP 8.2 or later, you can verify if the quotas are getting upgraded to the clustered Data ONTAP environment.