Usage accounting and limits

Storage quotas support two usage types that you can create to manage storage space: usage accounting and enforcement limits.

You can configure OneFS quotas by usage type to track or limit storage use. The accounting option, which monitors disk-storage use, is useful for auditing, planning, and billing. Enforcement limits set storage limits for users, groups, or directories.

Track storage limits without specifying a storage limit

The accounting option tracks but does not limit disk-storage use. Using the accounting option for a quota, you can monitor inode count and physical and logical space resources. Physical space refers to all of the space that is used to store files and directories, including data and metadata in the domain. Logical space refers to the sum of all files sizes, excluding file metadata and sparse regions. User data storage is tracked using logical-space calculations, which do not include protection overhead. As an example, by using the accounting option, you can do the following:

  • Track the amount of disk space that is used by various users or groups to bill each user, group, or directory for only the disk space used.

  • Review and analyze reports that help you identify storage usage patterns and define storage policies.

  • Plan for capacity and other storage needs.

Specify storage limits

Enforcement limits include all of the functionality of the accounting option, plus the ability to limit disk storage and send notifications. Using enforcement limits, you can logically partition a cluster to control or restrict how much storage that a user, group, or directory can use. For example, you can set hard- or soft-capacity limits to ensure that adequate space is always available for key projects and critical applications and to ensure that users of the cluster do not exceed their allotted storage capacity. Optionally, you can deliver real-time email quota notifications to users, group managers, or administrators when they are approaching or have exceeded a quota limit.

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If a quota type uses the accounting-only option, enforcement limits cannot be used for that quota.


The actions of an administrator who is logged in as root may push a domain over a quota threshold. For example, changing the protection level or taking a snapshot has the potential to exceed quota parameters. System actions such as repairs also may push a quota domain over the limit.

The system provides three types of administrator-defined enforcement thresholds.

Threshold type

Description

Hard

Limits disk usage to a size that cannot be exceeded. If an operation, such as a file write, causes a quota target to exceed a hard quota, the following events occur:

  • The operation fails

  • An alert is logged to the cluster

  • A notification is issued to specified recipients.

Writes resume when the usage falls below the threshold.

Soft

Allows a limit with a grace period that can be exceeded until the grace period expires. When a soft quota is exceeded, an alert is logged to the cluster and a notification is issued to specified recipients; however, data writes are permitted during the grace period.

If the soft threshold is still exceeded when the grace period expires, data writes fail, and a hard-limit notification is issued to the recipients you have specified.

Writes resume when the usage falls below the threshold.

Advisory

An informational limit that can be exceeded. When an advisory quota threshold is exceeded, an alert is logged to the cluster and a notification is issued to specified recipients. Advisory thresholds do not prevent data writes.