PowerScale OneFS Web Administration Guide

Usage accounting and limits

Storage quotas can perform two functions: they monitor storage space through usage accounting and they manage storage space through 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 consumption 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, metadata, and data protection overhead in the domain. There are two types of logical space:

• File system logical size: Logical size of files as per file system. Sum of all files sizes, excluding file metadata and data protection overhead.
• Application logical size : Logical size of file apparent to the application. Used file capacity from the application point of view, which is usually equal to or less than the file system logical size. However, in the case of a sparse file, application logical size can be greater than file system logical size. Application logical size includes capacity consumption on the cluster as well as data tiered to the cloud.

Storage consumption is tracked using file system logical size by default, which does 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.

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.