How to Set User/Group Disk Quotas on FreeBSD Operating System

Introduction

Disk quotas are an essential tool for system administrators managing multi-user FreeBSD systems. They allow administrators to control and limit the amount of disk space individual users or groups can consume. This capability is particularly important in shared environments such as educational institutions, web hosting services, or corporate networks where resources need to be fairly distributed among users.

FreeBSD offers a robust built-in quota system that can be configured to enforce soft and hard limits on both users and groups. This article provides a comprehensive guide to understanding, implementing, and managing disk quotas on FreeBSD systems.

Understanding Disk Quotas

Before diving into the implementation details, it’s important to understand the key concepts of disk quotas:

Types of Quotas

FreeBSD supports two primary types of quotas:

1. User Quotas: Limits disk usage for individual users
2. Group Quotas: Limits disk usage for groups of users

Quota Limits

For each type of quota, you can set two kinds of limits:

1. Soft Limits: Users can temporarily exceed these limits for a grace period
2. Hard Limits: Absolute limits that cannot be exceeded

Quota Metrics

Quotas can be applied to:

• Block Usage: The amount of disk space used in blocks (typically 512 bytes per block)
• Inode Usage: The number of files and directories (inodes) a user or group can create

Prerequisites

Before implementing disk quotas, ensure that:

1. You have root/superuser access to the FreeBSD system
2. The UFS filesystem is being used (the default for FreeBSD)
3. The kernel has quota support enabled (included by default in GENERIC kernel)

Step 1: Enable Quota Support in /etc/rc.conf

First, you need to enable quota support in your system’s configuration file:

# Enable quotas
echo 'quotas_enable="YES"' >> /etc/rc.conf

# Enable quota checking during boot
echo 'check_quotas="YES"' >> /etc/rc.conf

Step 2: Configure Filesystems for Quotas

Next, you need to modify the /etc/fstab file to enable quotas on the desired filesystems. Add the appropriate quota options (userquota and/or groupquota) to the filesystems:

# Original entry
/dev/ada0p2     /home     ufs     rw     2     2

# Modified entry with quota support
/dev/ada0p2     /home     ufs     rw,userquota,groupquota     2     2

You can enable either user quotas, group quotas, or both, depending on your requirements.

Step 3: Create Quota Database Files

After modifying /etc/fstab, you need to create the quota database files. First, mount the filesystem with the quota options:

# Remount the filesystem with quota options
mount -o update /home

Then, create the quota database files:

# Create the quota database files
quotacheck -avug

This command will create the necessary quota database files:

• /home/quota.user for user quotas
• /home/quota.group for group quotas

Step 4: Enable Quotas

Once the quota database files are created, you can enable quotas using the quotaon command:

# Enable quotas on all filesystems
quotaon -a

# Alternatively, enable quotas on a specific filesystem
quotaon /home

Step 5: Set Quota Limits

Now that quotas are enabled, you can set limits for users and groups. FreeBSD provides two main commands for this purpose:

1. edquota: For setting quotas through a text editor
2. setquota: For setting quotas directly from the command line

Using edquota

The edquota command opens a temporary file in the default text editor where you can set quota limits:

# Set quotas for a user
edquota username

# Set quotas for a group
edquota -g groupname

The temporary file will look something like this:

Quotas for user username:
/home: blocks in use: 65, limits (soft = 0, hard = 0)
       inodes in use: 7, limits (soft = 0, hard = 0)

Modify the soft and hard limits as needed. For example:

Quotas for user username:
/home: blocks in use: 65, limits (soft = 500000, hard = 550000)
       inodes in use: 7, limits (soft = 1000, hard = 1100)

This sets a soft limit of 500000 blocks (about 250MB) and a hard limit of 550000 blocks (about 275MB), as well as soft and hard limits for the number of inodes (files and directories).

Using setquota

The setquota command allows you to set quotas directly from the command line:

# Set quotas for a user
setquota -u username 500000 550000 1000 1100 /home

# Set quotas for a group
setquota -g groupname 1000000 1100000 2000 2200 /home

The parameters are:

1. Soft block limit
2. Hard block limit
3. Soft inode limit
4. Hard inode limit
5. Filesystem

Setting Grace Periods

You can set grace periods for soft limits using the edquota -t command:

edquota -t

This will open a temporary file where you can set grace periods:

Time units may be: days, hours, minutes, or seconds
Grace period before enforcing soft limits for users:
/home: block grace period: 7 days, file grace period: 7 days

Step 6: Copy Quota Settings

To apply the same quota settings to multiple users, you can use the -p option with edquota:

# Set quotas for user1
edquota user1

# Copy user1's quotas to user2 and user3
edquota -p user1 user2 user3

Step 7: Verify Quota Settings

To verify the quota settings, use the quota command:

# Check quotas for the current user
quota

# Check quotas for a specific user
quota username

# Check quotas for a specific group
quota -g groupname

For a more detailed report, use the repquota command:

# Generate a report for all quotas
repquota -a

# Generate a report for a specific filesystem
repquota /home

Step 8: Monitoring and Managing Quotas

Regular monitoring of quota usage is important for effective management. Here are some useful commands:

# Check usage for all users
repquota -a

# Check usage for a specific filesystem
repquota /home

# Check for users nearing their quota limits
repquota -a | grep "^-"

Advanced Configuration

Automating Quota Management

For larger systems, you might want to automate quota management. You can create scripts to:

1. Set default quotas for new users
2. Generate regular reports on quota usage
3. Alert administrators when users approach their limits

Quota Management with ZFS

If you’re using ZFS instead of UFS, the quota management process is different. ZFS has built-in quota support through properties:

# Set user quota on a ZFS dataset
zfs set userquota@username=250M zpool/home

# Set group quota on a ZFS dataset
zfs set groupquota@groupname=500M zpool/home

# Set a quota for the entire dataset
zfs set quota=10G zpool/home

ZFS also supports more advanced quota features like reservation and reference quotas.

Troubleshooting

Common Issues

1. Quotas not being enforced: Ensure that quotas are enabled with quotaon -a and that the correct options are set in /etc/fstab.

2. Missing quota database files: Run quotacheck -avug to recreate the quota database files.

3. Inconsistent quota reports: If quota reports show inconsistent data, run quotacheck -avug to rebuild the quota database.

4. Users unable to log in: If users are unable to log in due to exceeded quotas, you may need to increase their limits or remove some files.

Conclusion

Disk quotas are a powerful tool for managing disk space on FreeBSD systems. By implementing quotas, system administrators can ensure fair resource allocation, prevent disk space abuse, and maintain system stability.

Setting up quotas involves enabling quota support, configuring filesystems, creating database files, and setting appropriate limits. Regular monitoring and management are essential for maintaining an effective quota system.

FreeBSD’s quota system provides flexibility through soft and hard limits, as well as grace periods, allowing administrators to balance strict enforcement with user needs. Whether you’re managing a small office network or a large-scale server environment, disk quotas are an invaluable resource management tool.

For more detailed information, refer to the FreeBSD Handbook and man pages for the quota-related commands (quota, edquota, setquota, repquota, quotacheck, and quotaon).