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Overview of the quota process

Quotas can be soft or hard. Soft quotas cause ONTAP to send a notification when specified limits are exceeded, and hard quotas prevent a write operation from succeeding when specified limits are exceeded.

When ONTAP receives a request from a user or user group to write to a FlexVol volume, it checks to see whether quotas are activated on that volume for the user or user group and determines the following:

  • Whether the hard limit will be reached

    If yes, the write operation fails when the hard limit is reached and the hard quota notification is sent.

  • Whether the soft limit will be breached

    If yes, the write operation succeeds when the soft limit is breached and the soft quota notification is sent.

  • Whether a write operation will not exceed the soft limit

    If yes, the write operation succeeds and no notification is sent.

  • Differences among hard, soft, and threshold quotas
    Hard quotas prevent operations while soft quotas trigger notifications.
  • Understanding quota notifications
    Quota notifications are messages that are sent to the event management system (EMS) and also configured as SNMP traps.
  • 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.
  • 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 an 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 tree quotas work
    You can create a quota with a qtree as its target to limit how large the target qtree can become. These quotas are also called tree quotas.
  • How qtree changes affect quotas
    When you delete, rename, or change the security style of a qtree, the quotas applied by 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 Linux 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 Linux 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 Linux commands for calculating the data blocks in the volume or qtree.
  • Examples of quota configuration
    These examples help you understand how to configure quotas and read quota reports.