18.11. Disk Quotas

Disk quotas can be used to limit the amount of disk space or the number of files a user or members of a group may allocate on a per-file system basis. This prevents one user or group of users from consuming all of the available disk space.

This section describes how to configure disk quotas for the UFS file system. To configure quotas on the ZFS file system, refer to Section 20.4.8, “Dataset, User, and Group Quotas”

18.11.1. Enabling Disk Quotas

To determine if the FreeBSD kernel provides support for disk quotas:

% sysctl kern.features.ufs_quota
kern.features.ufs_quota: 1

In this example, the 1 indicates quota support. If the value is instead 0, add the following line to a custom kernel configuration file and rebuild the kernel using the instructions in Chapter 9, Configuring the FreeBSD Kernel:

options QUOTA

Next, enable disk quotas in /etc/rc.conf:

quota_enable="YES"

Normally on bootup, the quota integrity of each file system is checked by quotacheck(8). This program insures that the data in the quota database properly reflects the data on the file system. This is a time consuming process that will significantly affect the time the system takes to boot. To skip this step, add this variable to /etc/rc.conf:

check_quotas="NO"

Finally, edit /etc/fstab to enable disk quotas on a per-file system basis. To enable per-user quotas on a file system, add userquota to the options field in the /etc/fstab entry for the file system to enable quotas on. For example:

/dev/da1s2g   /home    ufs rw,userquota 1 2

To enable group quotas, use groupquota instead. To enable both user and group quotas, separate the options with a comma:

/dev/da1s2g    /home    ufs rw,userquota,groupquota 1 2

By default, quota files are stored in the root directory of the file system as quota.user and quota.group. Refer to fstab(5) for more information. Specifying an alternate location for the quota files is not recommended.

Once the configuration is complete, reboot the system and /etc/rc will automatically run the appropriate commands to create the initial quota files for all of the quotas enabled in /etc/fstab.

In the normal course of operations, there should be no need to manually run quotacheck(8), quotaon(8), or quotaoff(8). However, one should read these manual pages to be familiar with their operation.

18.11.2. Setting Quota Limits

To verify that quotas are enabled, run:

# quota -v

There should be a one line summary of disk usage and current quota limits for each file system that quotas are enabled on.

The system is now ready to be assigned quota limits with edquota.

Several options are available to enforce limits on the amount of disk space a user or group may allocate, and how many files they may create. Allocations can be limited based on disk space (block quotas), number of files (inode quotas), or a combination of both. Each limit is further broken down into two categories: hard and soft limits.

A hard limit may not be exceeded. Once a user reaches a hard limit, no further allocations can be made on that file system by that user. For example, if the user has a hard limit of 500 kbytes on a file system and is currently using 490 kbytes, the user can only allocate an additional 10 kbytes. Attempting to allocate an additional 11 kbytes will fail.

Soft limits can be exceeded for a limited amount of time, known as the grace period, which is one week by default. If a user stays over their limit longer than the grace period, the soft limit turns into a hard limit and no further allocations are allowed. When the user drops back below the soft limit, the grace period is reset.

In the following example, the quota for the test account is being edited. When edquota is invoked, the editor specified by EDITOR is opened in order to edit the quota limits. The default editor is set to vi.

# edquota -u test
Quotas for user test:
/usr: kbytes in use: 65, limits (soft = 50, hard = 75)
        inodes in use: 7, limits (soft = 50, hard = 60)
/usr/var: kbytes in use: 0, limits (soft = 50, hard = 75)
        inodes in use: 0, limits (soft = 50, hard = 60)

There are normally two lines for each file system that has quotas enabled. One line represents the block limits and the other represents the inode limits. Change the value to modify the quota limit. For example, to raise the block limit on /usr to a soft limit of 500 and a hard limit of 600, change the values in that line as follows:

/usr: kbytes in use: 65, limits (soft = 500, hard = 600)

The new quota limits take affect upon exiting the editor.

Sometimes it is desirable to set quota limits on a range of users. This can be done by first assigning the desired quota limit to a user. Then, use -p to duplicate that quota to a specified range of user IDs (UIDs). The following command will duplicate those quota limits for UIDs 10,000 through 19,999:

# edquota -p test 10000-19999

For more information, refer to edquota(8).

18.11.3. Checking Quota Limits and Disk Usage

To check individual user or group quotas and disk usage, use quota(1). A user may only examine their own quota and the quota of a group they are a member of. Only the superuser may view all user and group quotas. To get a summary of all quotas and disk usage for file systems with quotas enabled, use repquota(8).

Normally, file systems that the user is not using any disk space on will not show in the output of quota, even if the user has a quota limit assigned for that file system. Use -v to display those file systems. The following is sample output from quota -v for a user that has quota limits on two file systems.

Disk quotas for user test (uid 1002):
     Filesystem  usage    quota   limit   grace   files   quota   limit   grace
           /usr      65*     50      75   5days       7      50      60
       /usr/var       0      50      75               0      50      60

In this example, the user is currently 15 kbytes over the soft limit of 50 kbytes on /usr and has 5 days of grace period left. The asterisk * indicates that the user is currently over the quota limit.

18.11.4. Quotas over NFS

Quotas are enforced by the quota subsystem on the NFS server. The rpc.rquotad(8) daemon makes quota information available to quota on NFS clients, allowing users on those machines to see their quota statistics.

On the NFS server, enable rpc.rquotad by removing the # from this line in /etc/inetd.conf:

rquotad/1      dgram rpc/udp wait root /usr/libexec/rpc.rquotad rpc.rquotad

Then, restart inetd:

# service inetd restart

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