What Are Quotas?

Quotas enable system administrators to control the size of UFS file systems by limiting the amount of disk space and the number of inodes (which roughly corresponds to the number of files) that individual users can acquire. For this reason, quotas are especially useful on the file systems where user home directories reside. As a rule, public and /tmp file systems usually do not benefit as much from the establishment of quotas.

Setting up quotas involves these general steps:

1. Enable file system quotas by issuing a series of commands, ensuring that quotas are enforced each time the system is rebooted and the file system is mounted. Entries must be added to the /etc/vfstab file, and a quotas file must be created in the root of the file system.

2. After a quota is created for one user, the quota can be copied as a prototype to set up other user quotas.

3. Before quotas are turned on, another command checks for consistency by comparing the proposed quotas to the current disk usage to make sure there are no conflicts.

4. Finally, a command turns on the quotas for one or more file systems.

These steps ensure that quotas are automatically activated on a file system each time it is mounted. For step-by-step instructions, see Chapter 17, Managing Quotas (Tasks).

Once quotas are in place, they can be changed to adjust the amount of disk space or number of inodes that users can consume. Additionally, quotas can be added or removed as system needs change. For instructions on how to change quotas, disable individual quotas, or remove quotas from file systems, see Changing and Removing Quotas.