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Security Guide

Disk Quota System Overview

The disk quota system allows system administrators to control the number of files and data blocks that can be allocated to users or groups. The following sections provide further information about the disk quota system, its implementation, and use:

Understanding the Disk Quota System

The disk quota system, based on the Berkeley Disk Quota System, provides an effective way to control the use of disk space. The quota system can be defined for individual users or groups, and is maintained for each journaled file system.

The disk quota system establishes limits based on the following parameters that can be changed with the edquota command:

The soft limit defines the number of 1 KB disk blocks or files under which the user must remain. The hard limit defines the maximum amount of disk blocks or files the user can accumulate under the established disk quotas. The quota grace period allows the user to exceed the soft limit for a short period of time (the default value is one week). If the user fails to reduce usage below the soft limit during the specified time, the system will interpret the soft limit as the maximum allocation allowed, and no further storage is allocated to the user. The user can reset this condition by removing enough files to reduce usage below the soft limit.

The disk quota system tracks user and group quotas in the quota.user and quota.group files that reside in the root directories of file systems enabled with quotas. These files are created with the quotacheck and edquota commands and are readable with the quota commands.

Recovering from Over-Quota Conditions

To reduce file system usage when you have exceeded quota limits, you can use the following methods:

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